A/C question

[AutoVation]

I've been having lots of problems with the A/C and there have been several items fixed but it is still not working right.

After the car sat for 2 months while I worked on other things, I began having the problems. I had the blower only blowing on high so I replaced the control board (thanks BrianK!), that fixed that issue. Next I had the system inspected for leaks and had an o-ring leak fixed and the system changed to R-134. Now I am still having problems... here's the current situation:

• Hot air on driver side vents (85 deg or so), cooler air (70-75 deg) on the passenger side
• sight glass looks like boiling water (lots of bubbles)
• Low pressure side is showing 45-47psi, we didn't want to put more freon in and increase the pressure (normal should be 35-40psi)

So it appears my system is low on freon but I can't put more in without getting to a dangerous pressure. Do I just need to evacuate the entire system and refill with freon? I'm tending to think the R134 conversion was not done correctly and either air or oil was left in the lines. Thoughts?

 

[KooLaid]

The air duct issue says: Low Freon
The sight glass says: Low Freon or other issues possibly like air in the system, or dirty condensor, or blocked metering device (that meters the freon into the evaporator)
As for low side psi, what RPM are you pulling those numbers from?

How long ago was the last service performed?

From what my buddy tells me, it's an expensive car. Evacuate it, refill it.

 

[davidf]

When they did the 134 conversion did they replace the orfice tube also. They can get the slightest clogged and restrct flow. Personally I would have pd. more and stuck with R12.

 

[AutoVation]

The air duct issue says: Low Freon
The sight glass says: Low Freon or other issues possibly like air in the system, or dirty condensor, or blocked metering device (that meters the freon into the evaporator)
As for low side psi, what RPM are you pulling those numbers from?

How long ago was the last service performed?

From what my buddy tells me, it's an expensive car. Evacuate it, refill it.

The psi numbers were pulled at idle (800rpm or so).

The last service was done about 1 month ago. It worked when I drove off the lot, then 30 minutes later... hot on drivers side, cold on passengers side. Then a couple days later... hot on both sides. This was after the leak was fixed.

 

[AutoVation]

When they did the 134 conversion did they replace the orfice tube also. They can get the slightest clogged and restrct flow. Personally I would have pd. more and stuck with R12.

The service records from before I owned the car show it was in for refills 4 times in the 4 years before I bought it. I figured the 134 would work out in the long run. They've fixed one leak but there may be another.

Next plan...

Pull a vacuum on the system, check vacuum level and seal it. Let it sit for 1 hour and then check the vacuum level again. If there is a change, then find the leak. Refill system to correct level and the 30-32 psi.

If no leak, begin checking for blockages in the system. (Note that condenser fans are working correctly also).

 

[davidf]

100% agree on condensor fans. But if it's not cooling while driving down the road at a nominal speed, it's likely not the fans.

 

[Maxturbo]

What are your HIGH side pressure readings? Need that to better troubleshoot your prob , AH. :wink:

Your stated low end pressure and evidence of bubbles in the site glass are not uncommon at THAT idle RPM particularly w/R-134. Bring RPM's up to 1500-2000 engine revs (to achieve optimum optimum compressor speed), and w/cabin fan on high, observe both high and low pressure readings, and site glass condition.

Additionally...freon pressure readings are entirely dependent on heat LOAD. Try and create repetitive tests such as ambient temp, fan on max, doors open, etc.

Currently, it would appear that you have a freon leak (or leaks), but we need those testing parameters set and pressure readings to confirm. Also R-134 charge amounts should be about 30% less (given the same R-12 charge quantity requirement as OEM suggested) due to the differing expansion / cooling characteristics. High end pressure readings will be excessive, unless a larger capacity condenser is installed. Have you tried adding red dye leak detector yet? That and some SERIOUS "hand over hand" inspection of each and every fitting, line, hose and connection should find the leak. When under the car, look for possible line to clamp or body obstruction contact areas too that could wear a hole in the lines, causing leaks.

FWIW....R-134 is good when properly set up, but it's not the ole' R-12 that it replaced, so many will not achieve the same cooling results.