ac debug

[euclid]

New preasure switch, condensor, expansion valve and dryer. Vacuum down, holds a vacuum OK... not great but OK. I really need to replace my high and low side long lines.

Decided to go ahead and charge it up and look for leaks.

Compressor won't kick on. Per david's post here I jumped the black wire. Compressor kicks right on and runs fine.

W/ compressor off I'm reading about 50 psi low and 70 psi high side. Didn't run the compressor long enough to get a reading there.

My first thought was that I wired the new preasure switch wrong. The new (toyota) switch was marked differently than the origional, with no indicator of how to hook it up. I just guessed, based on the marking on the switch, how to hook it up. So, thinking this may be the problem, I swaped the wires. Still no compressor.

Thoughts?

 

[rchalmers3]

Greg, In your test did you try to jumper (bypass) the pressure switch or did you just apply power to the clutch?

I think your next step will be to go to the amplifier and pin out the powers, ground and output to the clutch. The amplifier is in the center of the circuit and lends itself to dividing up the potential areas of failure.

Rick

 

[kevinmrowland]

Hey Greg,
Tis the season for AC work.
The two YG wires for the pressure switch can go on either spade terminal. It is a go-no-go contact, no flow direction.
How much did you charge the AC with? How many ounces?
You can jump the pressure switch terminal as suggested to isolate that as the issue, but with your readings I think you just didn't put enough pressure in (new pressure switches can by faulty though)

 

[euclid]

OK, thanks fellas. I'm going to try a charge some more in the AM. I discovered a leak in the quick connect for the low side, so maybe I didn't get as much in as I thought.

I emptied 1 16 oz Pag oil /freon charge, 1 12 oz leak/freon, and 2 X 12 OZ cans, so I was sure I had enough in there, but maybe I lost some at the leaky quick connect.

 

[kevinmrowland]

Well, you should already be 16oz over charged at that rate.
What did you vacuum out the system with?

 

[euclid]

That's what I was thinking.

I have a horrible freight compressor driven vacuum. Pulled about 15 PSI for 30 mins.

 

[kevinmrowland]

Then you left it to hold? How long did the vacuum hold?
It is easier to keep vacuum that it is to keep pressure, so if there is any vacuum drop, there will certainly be pressure drop.
You can isolate everything to do with pressure by pulling the plug that goes to the PS with the two YG wires and jumping the terminals together. If all your pressure stuff checks out, then I would suspect the new PS.

 

[euclid]

OK, I have a leak, looks like it's the high line into the evap. I'll chase it next weekend.

 

[cruiser88]

Before charging next time Greg pressurize to 50 psi with nitrogen for a couple of hours and watch your manifold gauges for a drop.

Then vac to 29.92 or 30..... or the best you can get.

 

[NocalFJ60]

Greg,

You using a kit to replace the seals? You tired the o-ring AC seal kit Napa sells? I have a couple of leaks and need to replace all the seals.

Shows this for your 89 cruiser.
A/C System Seal Kit Item#: TEM801764 Price: $8.69

 

[euclid]

Damnit.

All new seals. Pushed cleaner through the condensor. Another new evaporator. New suction line. Another new dryer.

Holds a vacuum great, so I start preasurizing. I'm seeing perfect preasures on the low side - 21 LBS. High side is about 180 and rising. I'm thinking it's gonna work perfect. Starts cooling, about 10* below ambiant. Suction line is cooling off. Sight glass is clearing up.

All of the sudden my low side preassure drops to nothing, and I get no more cooling.

I'm thinking I have some trash in the system, probably in the expansion valve.

I'm going to go get one of those guns that suck the cleaner fluid up and push it through the system.

My question is this: Can I clean the expansion valve by pushing cleaner through the suction valve, and opening the discharge line? Or do I have to take the expansion valve off? Or, should I preasureinze the system in reverse of the freon flow?

 

[1972FJ55]

Hi,
It sounds like it's time for a new expansion valve. I don't know anybody who's had success flushing them. Denso OE valve=$36,
cheap aftermarket=$27.
Good luck,
Rex