Hey there,
I have a 1983 TransAm with 350 sbc and have replaced and upgraded ac components. I had it charged and it worked great for 20 minutes or so. I have checked continuity from the switches fuses and the clutch engages when I connect to the battery. When driving. The ac clutch will not engage. I'm wondering if I could have leaked out the refrigerant or do I have a a bad evaporator dryer connection.

Thanks for your thoughts.
Melissa

 

What's the pressure at the low side Schraeder valve? Can you make the compressor run for a few seconds (DON'T do it for any longer than that) by shorting the low-pressure shutoff switch? If so, what's the low-side pressure while it runs?

"Had it charged" is a VERY bad omen.

 

More details are necessary. What components did you replace? What are the brands of those components? What methodology did you use to charge the system? Did you evacuate the system? How much oil did you add to the compressor?

 

Hey, Thank you for the reply. This is progress thus far: I replaced the hoses, evaporator, condensor and diode. I replaced the AC clutch switch. I then took it to a mechanic to do the things I couldn't do like evacuate the system, replace orifice, and upgrade the connections.

I was able to make the compressor clutch engage and compressor run. While putting guage on the low side to check pressure, it was low at 6 percent. The High port however was NOT upgraded at the mechanic!! So, my plans are to change the fitting and get the guages on and see what pressures are and look for leaks.
Let me know if this sounds like a good plan.

 

That makes no sense. Pressure is measured in psi or kPa. If it has R-134A in it, pressure at the low side with the AC off should be around 75 - 120 psi depending on the ambient temp, and about 30 - 35 with it running. With R-12 the pressures will be slightly higher than that. I can't imagine that in 2023, they would have put 12 in it, though; that would have cost them at least $200 just for the gas (your cost would probably have been at least 1½ times that), and it's REALLY hard to get these days.

​​​​​​​What orifice tube did they put in it?

Does the compressor now come on normally when commanded by the controls inside the car?

With the compressor running, the return line (big one) should be cold, cold enough to have water condensing on it. Is it?

 

Hey there,
First, I am going to rent a manifold system to check pressures as I am still getting zero reading.
I looked at my mechanic invoice and it shows evacuation/recharge R134. Also shows ac adaptor retro kit but the high flow adapter is the original. I did purchase a gm retro part kit to be sure that the high side retrofit is the 3/8" and the low side looks correct at the 7/16". After verification, attached manifold and still nothing so going to recheck with rental.
I do not see a charge for replacing the orifice tube ( ugh). As for the return line, no it isn't cool.
I am pretty stumped at this point. Could this be an issue with the condensor end of things?
Thanks for the information!
Melissa

 

Does the compressor now come on normally when commanded by the controls inside the car?

 

Hey there,
No, the compressor no longer activates from inside controls consistently. In driving today, the ac clutch does activate but the compressor doesn't consistently cycle.
I appreciate your response and helping figure this out.
Melissa

 

OK, so post the pressures that result when you short out the cutoff switch on the accumulator, but don't run it that way for more than a few seconds if the low-side pressure goes below 20 psi or so.

Do you mind revealing your location and native language if it's not English?

 

Sounds good. Should have manifold guage rental this weekend. I'm in WY so I only need AC about 2 to 3 weeks..it's when I travel to the city that it would be handy.
I will keep you updated and I appreciate your assistance 😊

 

I rented manifold set today. Low side pressure 30 and while the ac clutch was engaging, reading fluctuating between 20 and 60,however, the high side is not registering more than 5! AC clutch and compressor then quite cycling again. I'm beginning to think there is more than 1 problem.
Let me know what you think.
Melissa

 

Sounds like the high side fitting isn't opening the valve. You're not actually getting a reading at all.

Sounds like low of refrigerant. Should never go below 35 or so while operating normally. What happens is, when the compressor comes on, it sucks the low side dry of Freon, making the pressure go real low; then after the cutoff switch shuts off the compressor, the pressure comes back up, and it turns on again. That's what happens when there's not enough in there. If you just let it sit there, it should stabilize at around 80 psi or so depending on the ambient temp, no matter how much or little is in there, as long as there's enough to occupy the whole volume.

Try putting some in. One can should at least get it to work.

Problem then is, whatever was in there before, went away. Only way that can happen is for it to leak out. You're most likely going to have to track down the leak. Soapy water (dish or laundry detergent) on all the fittings and hose ends, all around the compressor, etc., may locate it, if you're lucky.

 

" The High port however was NOT upgraded at the mechanic!! "

How did you get a reading at the high port if they didn't install the R-134 fitting?

 

Sounds like one of those adapter things.

I've never had very good luck with those... they often don't depress the Schrader valve in the OE fitting. Which is probably what happened here. Worse, if they DO depress the original valve, they tend very strongly to leeeeek.

 

Hey there,
Yes, they do leeeeek! The drastic change in our weather is going to put the AC issue on hold,but these are the latest findings:
-Definitely has leak at low point and will not consistently engage clutch.
-The lines to the condensor are VERY warm after a few minutes so I will need further investigation here.
For now, I'm driving as much as possible before the snow ❄️
Thanks for your valuable help!
Melissa