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Hello, 1982 owner. Got several questions regarding the AC.
1. Mine has a r134 retrofit, it doesn't work, and hasn't worked since I got the car. Im seeing the diagnostic steps in the factory manual, and some of the steps involve pressure readings with specific expected pressure numbers. Do these numbers still apply to my r134 retrofit, or is it just for the r-12
2. When going to the vent setting after the car has warmed up to operating temp, is your guys's air warm also, or is it about what the outside air temp is?
3. Can an r-12 compressor work with r134?
Are you planning on diy?
ready to purchase some tools?
gauges, vacuum pump..to get started..
same numbers? Probably close..can u use same compressor? Yes..
but i think you need to assess all the parts and test compressor first if unsure of history or oil..and a look at orifice screen.
stock up on walmart 134 on sale
Last edited by interpon; Jul 31, 2022 at 11:32 PM.
Are you planning on diy?
ready to purchase some tools?
gauges, vacuum pump..to get started..
same numbers? Probably close..can u use same compressor? Yes..
but i think you need to assess all the parts and test compressor first if unsure of history or oil..and a look at orifice screen.
stock up on walmart 124 on sale
Thanks. I already have tools. Vacuum pumps, gauges, and 2 manifolds. Only thing im lacking is a solid diagnostic process.
Where is the orifice screen?
So this is the current status of it:
I recently recharged the lines with new r134. The result is the low pressure line becomes very cold after the compressor has kicked in for a bit, with condensation dripping from underneath the lines. I have also verified there are no leaks. But the air coming out the vents is not cold at all. The compressor makes this grinding noise, but I wanna verify that its actually the compressor that's creating issues before I spend $150+ on a new one, hence why I was trying to follow the manual. If you know a better way though, that would be appreciated.
Is it the original condenser or was it changed for a newer parallel flow unit? R134 isn't as efficient in heat rejection, therefore a much larger condenser is needed (than R12). If it wasn't replaced, replace it with a modern Parallel Flow (important) Micro-channel condenser (also important). They have as much as 12x more surface area (in the same pkg). That's one of the keys in getting an R134a system to work properly, even if you keep the same evaporator core.
Secondly, is the oil. Mineral Oil was used with R12. That's not compatible with 134a. You almost need to remove the old compressor and dump the oil out ...and then flush it thoroughly (on the bench) ...let dry and put in PAG150 (or replace it with a Delco reman). But if you do that, you ought to replace the compressor front seal (all the seals would be best). R4 compressors, esp used ones, often leak around the front pump seal. Pretty easy to replace. Delco reman's are like $150 as I recall ...and they have a great rating on Amazon. Um, make sure you put the pressure sensor on the back of a new compressor ....if your 82 requires it.
In fact, all components need to be flushed thoroughly of the old oil. And the rubber refrigerant lines should be replaced with new barrier hose, because the old hoses will contain Mineral Oil soaked into them (and 134a leaks through the old rubber too). Just a little mineral oil will reek havoc with PAG ...and R4 compressors should use the "right" GM oil for Harrison compressors (check Amazon). What I read is that the R4 compressor requires oil that will foam in the compressor and keep it lubricated ...so it's critical to get the right oil (see link below). And of course install a new accumulator as well. But if you don't replace the condenser it just won't reject heat very well (with the original one), and won't blow very 'cold'. Just about any new condenser you'd buy will most likely use micro-channel technology. Check out Four-seasons direct-fit condensers (and hoses). You can call their tech line if you see the info you need.
Do all that and your system stands a real good chance of working properly.
Personally if me
i would evacuate…check screen..
compressor noise is never good..make sure belt tight
maybe this helps..this will initially give youan idea of compressor https://www.corvetteforum.com/forums...s-oriface.html
Last edited by interpon; Jul 31, 2022 at 11:45 PM.
Is it the original condenser or was it changed for a newer parallel flow unit? R134 isn't as efficient in heat rejection, therefore a much larger condenser is needed (than R12). If it wasn't replaced, replace it with a modern Parallel Flow (important) Micro-channel condenser (also important). They have as much as 12x more surface area (in the same pkg). That's one of the keys in getting an R134a system to work properly, even if you keep the same evaporator core.
Secondly, is the oil. Mineral Oil was used with R12. That's not compatible with 134a. You almost need to remove the old compressor and dump the oil out ...and then flush it thoroughly (on the bench) ...let dry and put in PAG150 (or replace it with a Delco reman). But if you do that, you ought to replace the compressor front seal (all the seals would be best). R4 compressors, esp used ones, often leak around the front pump seal. Pretty easy to replace. Delco reman's are like $150 as I recall ...and they have a great rating on Amazon. Um, make sure you put the pressure sensor on the back of a new compressor ....if your 82 requires it.
In fact, all components need to be flushed thoroughly of the old oil. And the rubber refrigerant lines should be replaced with new barrier hose, because the old hoses will contain Mineral Oil soaked into them (and 134a leaks through the old rubber too). Just a little mineral oil will reek havoc with PAG ...and R4 compressors should use the "right" GM oil for Harrison compressors (check Amazon). What I read is that the R4 compressor requires oil that will foam in the compressor and keep it lubricated ...so it's critical to get the right oil (see link below). And of course install a new accumulator as well. But if you don't replace the condenser it just won't reject heat very well (with the original one), and won't blow very 'cold'. Just about any new condenser you'd buy will most likely use micro-channel technology. Check out Four-seasons direct-fit condensers (and hoses). You can call their tech line if you see the info you need.
Do all that and your system stands a real good chance of working properly.
The r134 retrofit was done by a shop in new mexico, the compressor isn't stock and im fairly confident it was properly done when it was retrofit. I will check the condenser though.
Personally if me
i would evacuate…check screen..
compressor noise is never good..make sure belt tight
maybe this helps..this will initially give youan idea of compressor https://www.corvetteforum.com/forums...s-oriface.html
sweet. Ill do it. Since I just put in r134 into the lines, is it ok if I store and reuse it once I evacuate the lines?
Someone on this forum recommended the book "Just Needs a Recharge: The Hack Mechanic Guide to Vintage Air Conditioning" by Rob Siegel. Best advice I got here in regards to A/C. Solid advice in there for diagnosis. Likely you have a leak that needs addressed.
To answer your question:
1. You basically use less R134 than R12. The formula is (R12 Charge Specification x 0.9) – 0.25 lbs.
2. The vent picks up some ambient heat but check to make sure the heater hose shutoff is working when slider is on cold
3. Depends on the compressor but as mentioned it's the oil you need to worry about.
I just redid my 82 that was already converted after the compressor went bad, replaced everything but the evaporator and hard lines. Stuck with R134a but upgraded to a parallel condenser and it works great down here in the FL heat.
Ok thanks all. Also, as I mentioned before the low line at then condenser gets cold when letting the system run, does that mean that the condenser and evaporator are fine?
Ok thanks all. Also, as I mentioned before the low line at then condenser gets cold when letting the system run, does that mean that the condenser and evaporator are fine?
Not necessarily, it could be you have a charge which is likely too low if the line is cool but not sufficient cold air in cabin. If the low line is sweating and really cold, you are pretty certain you have a sufficient charge then check blend doors and heater shutoff.
Not necessarily, it could be you have a charge which is likely too low if the line is cool but not sufficient cold air in cabin. If the low line is sweating and really cold, you are pretty certain you have a sufficient charge then check blend doors and heater shutoff.
If by sweating, you mean it is picking up condensation and dripping water, then yes it is. I will also check the heater doors.
if the low pressure side is cold then the evaporator in the car is cold. no cold air means the heater is full of hot coolant and overpowering the ac. install a shut-off valve in either heater hose. also the flapper that closes off the heater doesn't close it off. but if no hot water in the heater it is less of an issue. all ac cars NEED a manual heater water shut off. the vacuum controlled valve doesn't work very well when it works. and it stopped working a couple decades ago...
if the low pressure side is cold then the evaporator in the car is cold. no cold air means the heater is full of hot coolant and overpowering the ac. install a shut-off valve in either heater hose. also the flapper that closes off the heater doesn't close it off. but if no hot water in the heater it is less of an issue. all ac cars NEED a manual heater water shut off. the vacuum controlled valve doesn't work very well when it works. and it stopped working a couple decades ago...
and even when working properly.. when you shut off car vacuum is lost and hot water gets in , agree a shut off helps
Thats a good point about the shut off valve. I did a quick vacuum test just now, I never get vacuum in the line that goes to the heater control valve. I put the ac in Normal, HTR and Vent mode, and moved the slider to cold and hot, nothing. When should I be getting vacuum?
also, the control valve as well as both of the lines are hot after like 5 mins running
and the diaphragm on the heater control valve hold vacuum just fine
Thats a good point about the shut off valve. I did a quick vacuum test just now, I never get vacuum in the line that goes to the heater control valve. I put the ac in Normal, HTR and Vent mode, and moved the slider to cold and hot, nothing. When should I be getting vacuum?
also, the control valve as well as both of the lines are hot after like 5 mins running
and the diaphragm on the heater control valve hold vacuum just fine
Anytime you move the COLD HOT slider lever to COLD you should get a vacuum signal to the heater hose shutoff valve.
It may be just a simple cable adjustment or the switch may just need a fresh application of vacuum grease.
The vacuum Switch you have on a 82 can be taken apart.
Same switch was used LATE 1979-1982
This is what the vacuum switch looks like.
It is on top of the heater box.
Anytime you move the COLD HOT slider lever to COLD you should get a vacuum signal to the heater hose shutoff valve.
It may be just a simple cable adjustment or the switch may just need a fresh application of vacuum grease.
The vacuum Switch you have on a 82 can be taken apart.
Same switch was used LATE 1979-1982
This is what the vacuum switch looks like.
It is on top of the heater box.
AC questions
