Prep work for A/C repair shop.

[Shern]

Basically the title.

A/C was converted to R-134 back in 2011 (P/O). Worked well for a couple of years, until last summer, whereby I imagine it sprung a leak. It no longer blows cold/cool/tepid...

I don’t have the tools or equipment to refurbish it all myself. I was however hoping there were a few things I could do to either save on labor hours, or at the very least isolate the issue to save on exploratory with my indie.

To be honest though, i find it all a little overwhelming and am not sure where to start. Vent system? Change expansion valve orings? Drier? Take it to a shop and ask them to pump it with dye? No idea where to start...

[johnscars]

I had mine checked and refilled with 134A recently for similar symptoms after 4-5 years. A/C mechanic's first procedure is to vacuum down the system (remove the old) and see if it holds vac or leaks. He said it still had 1/4 charge, and it was holding vac. So on his recommendation he refilled and it's blowing very cold.

After he finished he pointed out some built up shmeg clogging the heat exchanger coils in a small area behind the horn. Possibly the site of the slow leak.

[Usaguy]

Originally Posted by Shern

I don’t have the tools or equipment to refurbish it all myself

Autozone rents out gauges and a vacuum pump and if you return it within 3 months then you get all of your money back (free).

That's how I fixed my ac

Originally Posted by Shern

No idea where to start...

check the system with the gauges, check a low pressure switch with a meter, add UV dye wait until it's dark to see if there are any leaks(using a UV light), report back on here

[Shern]

That's interesting... didn't know their rental kit extended to A/C.

Assuming there's anything left, I imagine I'd want to empty the system of any residual gas before I start taking things apart. There must be evironmental/safety protocols for doing so?

Originally Posted by christuna

Autozone rents out gauges and a vacuum pump and if you return it within 3 months then you get all of your money back (free).

That's how I fixed my ac



check the system with the gauges, check a low pressure switch with a meter, add UV dye wait until it's dark to see if there are any leaks(using a UV light), report back on here

[Usaguy]

Originally Posted by Shern

That's interesting... didn't know their rental kit extended to A/C.

Assuming there's anything left, I imagine I'd want to empty the system of any residual gas before I start taking things apart. There must be evironmental/safety protocols for doing so?

Check your low pressure switch for continuity (no continuity means pressure too low or too high)then rent and hook up the gauges to your system, if there is no pressure in the system then everything's leaked out long ago


There is another way of checking for pressure but I won't write it on here

[Shern]

This is not something I'm familiar with... Can you tell me more?

I'm testing across both poles on the switch?

Originally Posted by christuna

Check your low pressure switch for continuity (no continuity means pressure too low or too high)then rent and hook up the gauges to your system, if there is no pressure in the system then everything's leaked out long ago


There is another way of checking for pressure but I won't write it on here

[BillGrissom]

Measure resistance across the 2 terminals on the pressure switch. It is screwed into the top of the filter/drier (right front engine bay "floor"). If pressure is OK (>~10 psi), the switch should be closed (<50 ohm). If pressure is too low, it will be open (infinity). BTW, you can install a better high & low "binary" switch for a later model, as I did, and with low refrigerant now is the time.

Your cheapest way out is to buy an R-134A recharge can w/ pressure gage at the auto-parts (~$20). Connect it to the low-pressure port (top hose, front) and read the pressure. Should have instructions to tell you if too low and you need to add, based on ambient temperature. Don't add too much refrigerant. You can save it for the future.

If you do have a refrigerant leak, it should leave oil around the leak. There are only a few fittings where it can leak and all have O-rings. They should have changed to HBNR O-rings (usually green) when changing to R-134A, but may not have. The toughest ones to change are at the expansion valve on passenger cabin side behind and below the glove-box.

I had a return (suction) hose leak in the middle and left a green oily mess on top of the air filter housing (1985 CA "trashcan" style). I had added green flourescent die. I replaced the rubber using my Master-cool ferrule crimper. If the shaft seal on your compressor is leaking, you might not notice the refrigerant oil if it sits in the grub zone like on a W123 engine.

[Shern]

Very helpful, Bill. Thank you.

Will do this check and report back.

My hunch is that it’s the compressor itself that is leaking. It is a little oily and likely the only part of the system that’s still original. I haven’t used the r134a cans for that very reason. I was concerned I’d lost oil and didn’t want to risk the compressor seizing.

[Shern]

Definitely not open. Resistance is about the same as when I touch the two probes together… Does that mean I have pressure? And if so why would I not be getting cold air? My compressor works.

[Usaguy]

Originally Posted by Shern

My compressor works.

hook up high and low pressure gauges and tell us the readings you're getting