Adding gas won't cause evaporator temp to drop, it'll increase. Might be slight overcharge, depending on several things. You didn't give ambient temperature or temperature of evaporator and condenser outlet tubing. Was the evaporator restrictive orifice (refrigerant expansion device) confirmed clean and/or replaced? Remember, the compressor oil must be carried through the system with the refrigerant so if refrigerant is too low the oil will be washed out of the compressor by vapor and get trapped in the evaporator, never returning to the compressor.
How was the return suction line, should be very cold and sweating, Just up the charge slowly measuring the discharge temp with a digital thermometer to obtain the coldest temp you can, watch the sight glass and along the way. If the discharge starts to rise then stop and perhaps let some freon out. Also, I would do this on a hot summers day if at all possible. Please let us know how it works out.
Yours is doing the opposite of mine. Low side isn't really moving, even with more revs. High side gets higher with more 152 added. Not really ice cold and I'm way over charged. Like 300psi on the high side. More 152 I feed it, colder it gets out of the vent. Only getting 46F vent temps. Going to swap the TXV and drier this weekend.
I converted my 01 Honda Civic EX to 152a. Gets on average 3 to 4 degrees colder than the 134a did and has lower pressures. I use 12.5 oz charge as there is a .64 ratio to 134a charge oz of 19.4. I even used it to recharge my friends cube freezer and it's been working well also.
Low side should be around 25-30 at idle. High around 150'ish at idle. When charging open all car doors to keep compressor ON. Put on outside air during a hot day with fan on 3 out of 4 for example. You MUST weigh in the charge of 64% of an R-152A charge. Don't know for an R-12 car. Easy look up.
I know what's happening with your AC system. I think you may not have filled it with enough R152a. I looked it up and your car is supposed to normally take in 30 oz of R12. R152a molecular weight is 66.05, and R12 is 120.91. So you take 66.05 / 120.91 = about 0.55... so you will use 55% of R152a as you would for R12. So 30 oz * 0.55 = 16.5 oz of R152a. You will need 2 - 10oz cans. It is very important that you pull out as much of the R152a as possible. Majority of people leave at least 3 oz remaining in the first can. To pull every last bit from the first can you must raise the rpm of the engine to as high as you need to in order to bring the low side to as little as pressure as possible, this will lower the pressure from the can, which means pull out as much as possible. Close the low pressure valve while holding the rev at its lowest pressure possible, this will prevent the R152a from returning to the can. Then you can move on to the second can. Second can use about half. One thing to know about R152a, its that it is not that great from idle to about 1000 rpm. One solution for this is to continue to add just a little more R152a (about 1 or 2 oz) until there is not need to rev the engine above 1000 rpm, but it may cause just a little more drag on your engines power while driving with the added pressure. Notice if revving lowers AC temps. I do not recommend going past the suggested ounces. Maybe raise the engine's idle a little bit instead. When revved, High side should be at about 200psi, Low side can be just about anything, I rather have it as low as possible. Being that R152a molar weight is lower, the variation in temps will be greater compared to R12 and R134. This means that R152a might be so-so at idle, but R152a will get insanely cold at higher rpms and while driving. Definitely colder than the other two. I am assuming that you pulled a vacuum prior to filling up on the refrigerant, if not, you must, or else risk damaging the compressor. Older system designs seem to not be as effective as newer systems. My 94 Sentra, I experience what you might be experiencing, but my 03 S2000 & 06 Civic Si, it is cold at idle but crazy cold while driving. Sentra has completely new AC system too. Hope this helps. Ultimately, I think you might either be a little under on the correct ounces needed (don't overfill) or try raising the idle a little bit.
+Eddie Trevizo sorry for the late reply, i did not like the low side pressure if i would of kept charging it the low side would be about 80 while the high would of maybe been at 200 and the ambient temperature outside would be around 78-82 F and still not cold at the vents. I bought an air conditioning book and it said that when i get the pressure readings i have (at idle) that it would be a bad compressor reed valves letting in some of the high pressure gas into the low pressure side, without effectively increasing the pressure for the high side. Thank you for you in depth answer!
+Alfonso Perez Ouch, that sux bro. Yeah 80 low is way too high in pressure. Does sound like a bad leak of high pressure somewhere, most likely com pressure because by design we want the expansion valve to release the high pressure to low pressure (goes cold), but with a low side of 80 at idle, that's crazy high especially using R152a. I have mine at about 30psi low and about 190psi high or just about all my vehicles, gets crazy cold temps at the vent. Good luck man.
Yup, once I switched to R152a, I would never think of switching back to R134a. Gets way colder, especially in the highway, but also the drag it has on the motor is literally about half up until about 2000rpms, then feels like its not even on after that. Both of these benefits are directly related to the difference in the molecular weight from R134a to R152a (65%).
You have to change the TXV as R152 has different operating characteristic. Read : www.sae.org/altrefrigerant/presentations/presw-hill.pdf And you have to use cross flow condenser..
it would not be an evaporator cooling issue foremost because the pressure never gets up to operating spec (and also it was 87° at night). i had a cross flow condenser with 3/8 tubing should be enough even if multiflow is more efficient it ended up being a compressor reed problem
Adding gas won't cause evaporator temp to drop, it'll increase. Might be slight overcharge, depending on several things. You didn't give ambient temperature or temperature of evaporator and condenser outlet tubing. Was the evaporator restrictive orifice (refrigerant expansion device) confirmed clean and/or replaced?
Remember, the compressor oil must be carried through the system with the refrigerant so if refrigerant is too low the oil will be washed out of the compressor by vapor and get trapped in the evaporator, never returning to the compressor.
How was the return suction line, should be very cold and sweating, Just up the charge slowly measuring the discharge temp with a digital thermometer to obtain the coldest temp you can, watch the sight glass and along the way. If the discharge starts to rise then stop and perhaps let some freon out. Also, I would do this on a hot summers day if at all possible. Please let us know how it works out.
How much oil was added after the system rebuild?
Did you pull a "Vacuum"
Yours is doing the opposite of mine. Low side isn't really moving, even with more revs. High side gets higher with more 152 added. Not really ice cold and I'm way over charged. Like 300psi on the high side. More 152 I feed it, colder it gets out of the vent. Only getting 46F vent temps. Going to swap the TXV and drier this weekend.
I converted my 01 Honda Civic EX to 152a. Gets on average 3 to 4 degrees colder than the 134a did and has lower pressures. I use 12.5 oz charge as there is a .64 ratio to 134a charge oz of 19.4. I even used it to recharge my friends cube freezer and it's been working well also.
well it's good to hear someone out there is doing better, i ended up junking the car do to an unrelated incident
So what was the outcome? Was it a stuck open TXV?
Low side should be around 25-30 at idle. High around 150'ish at idle. When charging open all car doors to keep compressor ON. Put on outside air during a hot day with fan on 3 out of 4 for example. You MUST weigh in the charge of 64% of an R-152A charge. Don't know for an R-12 car. Easy look up.
I know what's happening with your AC system. I think you may not have filled it with enough R152a. I looked it up and your car is supposed to normally take in 30 oz of R12. R152a molecular weight is 66.05, and R12 is 120.91. So you take 66.05 / 120.91 = about 0.55... so you will use 55% of R152a as you would for R12. So 30 oz * 0.55 = 16.5 oz of R152a. You will need 2 - 10oz cans.
It is very important that you pull out as much of the R152a as possible. Majority of people leave at least 3 oz remaining in the first can. To pull every last bit from the first can you must raise the rpm of the engine to as high as you need to in order to bring the low side to as little as pressure as possible, this will lower the pressure from the can, which means pull out as much as possible. Close the low pressure valve while holding the rev at its lowest pressure possible, this will prevent the R152a from returning to the can. Then you can move on to the second can.
Second can use about half.
One thing to know about R152a, its that it is not that great from idle to about 1000 rpm. One solution for this is to continue to add just a little more R152a (about 1 or 2 oz) until there is not need to rev the engine above 1000 rpm, but it may cause just a little more drag on your engines power while driving with the added pressure. Notice if revving lowers AC temps. I do not recommend going past the suggested ounces. Maybe raise the engine's idle a little bit instead.
When revved, High side should be at about 200psi, Low side can be just about anything, I rather have it as low as possible.
Being that R152a molar weight is lower, the variation in temps will be greater compared to R12 and R134. This means that R152a might be so-so at idle, but R152a will get insanely cold at higher rpms and while driving. Definitely colder than the other two.
I am assuming that you pulled a vacuum prior to filling up on the refrigerant, if not, you must, or else risk damaging the compressor.
Older system designs seem to not be as effective as newer systems. My 94 Sentra, I experience what you might be experiencing, but my 03 S2000 & 06 Civic Si, it is cold at idle but crazy cold while driving. Sentra has completely new AC system too.
Hope this helps.
Ultimately, I think you might either be a little under on the correct ounces needed (don't overfill) or try raising the idle a little bit.
+Eddie Trevizo sorry for the late reply, i did not like the low side pressure if i would of kept charging it the low side would be about 80 while the high would of maybe been at 200 and the ambient temperature outside would be around 78-82 F and still not cold at the vents. I bought an air conditioning book and it said that when i get the pressure readings i have (at idle) that it would be a bad compressor reed valves letting in some of the high pressure gas into the low pressure side, without effectively increasing the pressure for the high side. Thank you for you in depth answer!
+Alfonso Perez Ouch, that sux bro. Yeah 80 low is way too high in pressure. Does sound like a bad leak of high pressure somewhere, most likely com pressure because by design we want the expansion valve to release the high pressure to low pressure (goes cold), but with a low side of 80 at idle, that's crazy high especially using R152a. I have mine at about 30psi low and about 190psi high or just about all my vehicles, gets crazy cold temps at the vent. Good luck man.
Thank you sir and do all you vehicle run r152a?
Yup, once I switched to R152a, I would never think of switching back to R134a. Gets way colder, especially in the highway, but also the drag it has on the motor is literally about half up until about 2000rpms, then feels like its not even on after that. Both of these benefits are directly related to the difference in the molecular weight from R134a to R152a (65%).
How would you calculate this for a R134a System? Im wanting to try this on my 94 Chevy truck.
You have to change the TXV as R152 has different operating characteristic.
Read : www.sae.org/altrefrigerant/presentations/presw-hill.pdf
And you have to use cross flow condenser..
it would not be an evaporator cooling issue foremost because the pressure never gets up to operating spec (and also it was 87° at night). i had a cross flow condenser with 3/8 tubing should be enough even if multiflow is more efficient it ended up being a compressor reed problem
+Alfonso Perez ment to say condenser
Undercharged.