No experience in HVAC but a fair amount of working with control wiring. I've noticed there are people that have knowledge but are unable to explain it, people that can explain it but only those with similar knowledge will understand them, and rare gems that know it well enough to explain it in a way that even the most inexperienced person can understand. The latter seems to be the case with this channel.
Have been in the field for 20 years never saw any explanation like this even in college I wish you could explain the way outdoor fan shots off during defrost cycle
Hi Mike, Your videos are really helpful for what I try to install. When I renovated my house last year, I installed floor heating(only pvc pipe), but not connected with water heater. In order to complete it, I just need thermostat, defrost control board, hot water recirculation pump, 24v/120v relay and 120/24v xfmr. Then, R, C, Y connection, right? It just needs water pump on/off based on temperature setting. Is there any simple kit for this system?
Question, I have a Carrier4 ton heat pump. My outdoor fan stops running intermittently. Of course I replaced the start capacitor . Since the fan wiring goes through a relay on the defrost PC I have ordered a replacement board. One thing I noted was that the large 330 ohm resistor runs hot. What is the purpose of this resistor, should it normally be running hot. I’m a do it seller and a retired electronic tech.
My first guess would be the fan is overheating. They often have thermal overload switches in them like compressors do. Have you checked the amperage draw on the motor yet?
I liked the explanation. I have a question. I have a trane unit and every time I turn the heat on even when outside temp is 50 and I raise my house temp from 68 to 69 just one degree the aux heat comes on
I've got an 11 year old Ruud/Rheem heat pump(U/RPNL-0307JAZ) that's going into a defrost cycle every time it gets a call for heat when the ambient temp's below freezing. The unit gets a call for heat, automatically goes into a defrost cycle, then operates normally until the next new call for heat. I'm a homeowner, so I'm doing a bit of a parts cannon approach until I get to the refrigerant side of things that will require a service call from a pro. I've replaced the run capacitor and added a hard start kit. After educating myself a bit, I'm starting to think there might be a problem with the logic chip on the defrost control board where it's not counting operating time correctly and always thinks it needs to defrost. I've ordered a new defrost control board and sensor, but I'm looking for ideas if that doesn't solve the problem. A second problem is that the original HVAC installer back in '78 when the house was built decided to only use a 4-conductor wire to the heat pump. That means I don't have a spare wire to hook up the W2 defrost circuit to activate the heat strips during defrost. It makes it a bit uncomfortable when it goes into defrost every heating cycle from 15-32 degrees ambient. My backup heat is electric, so I'm trying to run the heat pump as low as I can go to keep the electric bill down in the winter(I'm on the border of IECC climate zones 6 & 7 - as I type this it's currently 7 degrees outside and I'm fully on electric resistive heat). The heat pump and air handler are separated by 15' of completely finished space, so I think my only answer will be to live with it this winter, then open up walls and run a new 6- or 8-conductor wire next summer. But I'm interested if anyone has any other ideas.
11 месяцев назад
thnk U for the info here. But i have a question. What voltage is on the C terminal, if the R terminal has 24v.?
Hey Mike - I'm trying to trace out a low voltage short on my heat pump/hvac system that's blowing my 5amp fuse intermittently and I found that on the Defrost Control Board, I find continuity between Y and O - and I'm unsure if that's normal? Same for R and C. In additional, Y and O also has continuity to Ground. Power to all units were off while I was testing for continuity to find a wire that was contacting ground.
Neither Y or O should have continuity to ground or each other. Kind of sounds like the two wires are pinched somewhere and contacting metal. First place I would check is right where the T-stat wire first enters into the condensing unit, or same spot up by the air handler.
@@JerseyMikeHVAC Thanks for the quick reply Mike - the continuity between O ad Y happens at the terminal on the Defrost Control Board itself(I disconnected the T-stat wires and tested the prongs on the board and found the continuity) - so I can't tell if the board is bad in this case - however the system still runs just fine except for the intermittent shorts
@@JerseyMikeHVAC Hey Mike! Wanted to follow up back here and thank you for answering my questions above. I might have finally gotten the fix down after hours of chasing down a grounded wire. It seems the main issue was a dead relay on my Defrost Control Board. I had a reddit user call it out but wasn't fully convinced til I noticed that the Fuse would be blown after running for about 90 minutes or so, which was aligned to the defrost cycles, so I figured it must have been something defrost related. Bought a new defrost control board, swapped it out, and it looks like it's been running all night without popping a fuse. Here's to hopping it stays this way.
Ran into a Nordine heat pump . Defrost board had a M and SW connectors . Wiring diagram didn’t have a legend . Do you know what these are for or mean ?
Had a hard time finding the model number, but I got some info from a manual on another model. The SW terminal is the return voltage for the hi/lo pressure switch circuit that the board sends out on the PRESS terminal to prove the circuit. The M terminal completes a circuit to activate the compressor contactor off the Y signal, and its purpose to provide some kind of control when connected to an economizer. I don't know exactly in this case what parameter in an economizer would cut power to the contactor, but my first guess is to allow the economizer to shut down the system on a fire damper/smoke detection switch. If there is a molex plug jumper connected to the econ molex plug with a jumper wire between 4 and 6 terminals, this is just a bypass that allows the Y signal to reach the contactor when an economizer is not installed. So basically, either way, power from the thermostat to the contactor runs through that M terminal.
thank you, you need to make o e of those HVAC for dummies books. I have a question so my Trane TWN024C100A2. runs normally for some time then the fan will stop and not run. board 21C140501G18 - CNT1923 then flashes 3 times, won't go to normal unless breakers reset. my unit has a coil thermostat along the bottom outer edge, connected to coil on control board and the ambient thermostat a little further away, plugged into ambient on the board too, my question is that upon inspection I noticed that the defrost temperature switch THT00811 has two wires they start off blue with white stripes, then turns purple with white stripes, I'm sure its faded over time, but only has one wire connected to the contractor, and the other wire capped off, the control board does not have pins specifically for defrost, I can't find any help.
Thank you for the response, I have not, just yet, but now that you bring it up, I’ll be calling someone to check that. Just been doing some maintenance, replaced capacitors and relay, and ran across the discharge line temp switch only having one wire connected to T2 and the other capped off. from the diagrams it shows the sump htr wired to the L1 terminal on the contactor, the other sump wire to one of the wires on temp switch, then the 2nd wire on the temp switch to the T2 on the contactor, what I have is one wire from the temp switch on T2, and the sump htr wires directly connected to L1 and L2 on the contactor. Looks like the switch is bypassed. I saw a photo of the same model heat pump and one of the temp switch wires and the other sump htr wire were wired together
Can you please guide me what could be wrong? I opened the unit and saw a DS2 fault light blinking 3 flashes and it looks like low pressure switch open. I cycled power and it went away then I tried to turn heat on and same thing happened the aux heat came on right away. This time I didnot see and fault I check across the Low pressure switch and it looks closed to me. Also when the aux heat was on the compress fan started running aswell.
Different models and years have different codes, so I can't really confirm it's a pressure switch issue. It's difficult to narrow it down with so many possibilities and no access to testing.
@@JerseyMikeHVAC so I checked the pressures and when in heat mode the pressures looks 60 psi and when I switch to cool the pressure drops to 0 and gets my system in hard lockout.
We pumped some Freon yesterday Than I turned heat on but it’s not very effective. Than I turned it on cooling I just went in a hard lock out The lockout is when the low pressure switch is triggered a few times
![Noob To Max With DRAGON REWORK In Blox Fruits [FULL MOVIE]](http://i.ytimg.com/vi/LnBMOinoOvA/mqdefault.jpg)
Best explanation of the defrost control that I've seen. Nicely done.
Great explanation, now everything makes sense after 2 years of being in the field
Perfect. Love hearing that.
Isn’t even crazy how we can go so long without knowing something fully lol.
Best teacher ! Thanks Mike!!!!!
No experience in HVAC but a fair amount of working with control wiring. I've noticed there are people that have knowledge but are unable to explain it, people that can explain it but only those with similar knowledge will understand them, and rare gems that know it well enough to explain it in a way that even the most inexperienced person can understand. The latter seems to be the case with this channel.
Outstanding explanations, Thank you.
Have been in the field for 20 years never saw any explanation like this even in college
Thank you sir!!! I mainly work on straight AC and needed this.
Unbelievable explanation your the best
Well presented J M ... Thx for your time
Thank you
Incredible knowledge, such brief explanation how heat pump operation works thanks alot
You are most welcome
Thanks for sharing your knowledge Mike.
Thank you these videos help me more as a tech
You're welcome, brother.
you are a great person
Thanks I'm just starting on my a.c journey this is very very helpful for school starts
Great videos brother!!
Wow! THANK YOU!!!!!
You're welcome!
Have been in the field for 20 years never saw any explanation like this even in college I wish you could explain the way outdoor fan shots off during defrost cycle
I have a video here that explains it pretty well: ruclips.net/video/F88Y9NkvtQw/видео.html
Hi Mike,
Your videos are really helpful for what I try to install.
When I renovated my house last year, I installed floor heating(only pvc pipe), but not connected with water heater.
In order to complete it, I just need thermostat, defrost control board, hot water recirculation pump, 24v/120v relay and 120/24v xfmr.
Then, R, C, Y connection, right?
It just needs water pump on/off based on temperature setting.
Is there any simple kit for this system?
Honestly, I'm not familiar with a hot water heater defrost control board radiant heating arrangement to advise on this one.
Thanks
Welcome
Question, I have a Carrier4 ton heat pump. My outdoor fan stops running intermittently. Of course I replaced the start capacitor . Since the fan wiring goes through a relay on the defrost PC I have ordered a replacement board. One thing I noted was that the large 330 ohm resistor runs hot. What is the purpose of this resistor, should it normally be running hot. I’m a do it seller and a retired electronic tech.
My first guess would be the fan is overheating. They often have thermal overload switches in them like compressors do. Have you checked the amperage draw on the motor yet?
I liked the explanation.
I have a question.
I have a trane unit and every time I turn the heat on even when outside temp is 50 and I raise my house temp from 68 to 69 just one degree the aux heat comes on
Is AUX heat the only heating you have or a secondary heat?
I've got an 11 year old Ruud/Rheem heat pump(U/RPNL-0307JAZ) that's going into a defrost cycle every time it gets a call for heat when the ambient temp's below freezing. The unit gets a call for heat, automatically goes into a defrost cycle, then operates normally until the next new call for heat.
I'm a homeowner, so I'm doing a bit of a parts cannon approach until I get to the refrigerant side of things that will require a service call from a pro. I've replaced the run capacitor and added a hard start kit. After educating myself a bit, I'm starting to think there might be a problem with the logic chip on the defrost control board where it's not counting operating time correctly and always thinks it needs to defrost. I've ordered a new defrost control board and sensor, but I'm looking for ideas if that doesn't solve the problem.
A second problem is that the original HVAC installer back in '78 when the house was built decided to only use a 4-conductor wire to the heat pump. That means I don't have a spare wire to hook up the W2 defrost circuit to activate the heat strips during defrost. It makes it a bit uncomfortable when it goes into defrost every heating cycle from 15-32 degrees ambient. My backup heat is electric, so I'm trying to run the heat pump as low as I can go to keep the electric bill down in the winter(I'm on the border of IECC climate zones 6 & 7 - as I type this it's currently 7 degrees outside and I'm fully on electric resistive heat). The heat pump and air handler are separated by 15' of completely finished space, so I think my only answer will be to live with it this winter, then open up walls and run a new 6- or 8-conductor wire next summer. But I'm interested if anyone has any other ideas.
thnk U for the info here. But i have a question. What voltage is on the C terminal, if the R terminal has 24v.?
The common just completes any 24v circuit to allow voltage to flow. It shouldn't read anything by itself.
Hey Mike - I'm trying to trace out a low voltage short on my heat pump/hvac system that's blowing my 5amp fuse intermittently and I found that on the Defrost Control Board, I find continuity between Y and O - and I'm unsure if that's normal? Same for R and C. In additional, Y and O also has continuity to Ground. Power to all units were off while I was testing for continuity to find a wire that was contacting ground.
Neither Y or O should have continuity to ground or each other. Kind of sounds like the two wires are pinched somewhere and contacting metal. First place I would check is right where the T-stat wire first enters into the condensing unit, or same spot up by the air handler.
@@JerseyMikeHVAC Thanks for the quick reply Mike - the continuity between O ad Y happens at the terminal on the Defrost Control Board itself(I disconnected the T-stat wires and tested the prongs on the board and found the continuity) - so I can't tell if the board is bad in this case - however the system still runs just fine except for the intermittent shorts
@@life.b.s Where are you getting continuity to ground?
@@JerseyMikeHVAC Hey Mike! Wanted to follow up back here and thank you for answering my questions above. I might have finally gotten the fix down after hours of chasing down a grounded wire. It seems the main issue was a dead relay on my Defrost Control Board. I had a reddit user call it out but wasn't fully convinced til I noticed that the Fuse would be blown after running for about 90 minutes or so, which was aligned to the defrost cycles, so I figured it must have been something defrost related. Bought a new defrost control board, swapped it out, and it looks like it's been running all night without popping a fuse. Here's to hopping it stays this way.
Ran into a Nordine heat pump . Defrost board had a M and SW connectors . Wiring diagram didn’t have a legend . Do you know what these are for or mean ?
M may be a manual mode option. Not sure about SW but could be a temp switch. Have the model number?
@@JerseyMikeHVAC I have the wiring diagram if you’d like to see it .
Model number Q6E-x48k
Nordyne
Had a hard time finding the model number, but I got some info from a manual on another model.
The SW terminal is the return voltage for the hi/lo pressure switch circuit that the board sends out on the PRESS terminal to prove the circuit.
The M terminal completes a circuit to activate the compressor contactor off the Y signal, and its purpose to provide some kind of control when connected to an economizer. I don't know exactly in this case what parameter in an economizer would cut power to the contactor, but my first guess is to allow the economizer to shut down the system on a fire damper/smoke detection switch. If there is a molex plug jumper connected to the econ molex plug with a jumper wire between 4 and 6 terminals, this is just a bypass that allows the Y signal to reach the contactor when an economizer is not installed. So basically, either way, power from the thermostat to the contactor runs through that M terminal.
thank you, you need to make o e of those HVAC for dummies books. I have a question so my Trane TWN024C100A2. runs normally for some time then the fan will stop and not run. board 21C140501G18 - CNT1923 then flashes 3 times, won't go to normal unless breakers reset. my unit has a coil thermostat along the bottom outer edge, connected to coil on control board and the ambient thermostat a little further away, plugged into ambient on the board too, my question is that upon inspection I noticed that the defrost temperature switch THT00811 has two wires they start off blue with white stripes, then turns purple with white stripes, I'm sure its faded over time, but only has one wire connected to the contractor, and the other wire capped off, the control board does not have pins specifically for defrost, I can't find any help.
3 flash codes on Trane Defrost board is an indication of low pressure in the system. Have the refrigerant levels been checked lately?
Thank you for the response, I have not, just yet, but now that you bring it up, I’ll be calling someone to check that. Just been doing some maintenance, replaced capacitors and relay, and ran across the discharge line temp switch only having one wire connected to T2 and the other capped off. from the diagrams it shows the sump htr wired to the L1 terminal on the contactor, the other sump wire to one of the wires on temp switch, then the 2nd wire on the temp switch to the T2 on the contactor, what I have is one wire from the temp switch on T2, and the sump htr wires directly connected to L1 and L2 on the contactor. Looks like the switch is bypassed. I saw a photo of the same model heat pump and one of the temp switch wires and the other sump htr wire were wired together
In your opinion what is the issue?
I can't say with certainty without looking at it myself, but based on what you're telling me, I'd strongly suspect a plugged filter dryer.
Where would that be inside coils or outside coils?
My heat strips come on instantly, and my heat pump never kicks on. Works fine in cool mode. Any suggestions?
Could be a few things, but a stuck reversing valve is not uncommon.
Turned out to be a bad thermostat.
Can you please guide me what could be wrong?
I opened the unit and saw a DS2 fault light blinking 3 flashes and it looks like low pressure switch open.
I cycled power and it went away then I tried to turn heat on and same thing happened the aux heat came on right away. This time I didnot see and fault
I check across the Low pressure switch and it looks closed to me.
Also when the aux heat was on the compress fan started running aswell.
Different models and years have different codes, so I can't really confirm it's a pressure switch issue. It's difficult to narrow it down with so many possibilities and no access to testing.
@@JerseyMikeHVAC so
I checked the pressures and when in heat mode the pressures looks 60 psi and when I switch to cool the pressure drops to 0 and gets my system in hard lockout.
Do you have a filter dryer in the lineset? Maybe internally in the condensing unit? Or could be a bad TXV.
@@ananddesai1826
I have bi direction filter
Does the copper line feel like different temperatures on each side of the filter when the system is running?
@@JerseyMikeHVAC yes
That may be your issue right there. @@ananddesai1826
We pumped some Freon yesterday
Than I turned heat on but it’s not very effective.
Than I turned it on cooling I just went in a hard lock out
The lockout is when the low pressure switch is triggered a few times
@@JerseyMikeHVAC the TXV?