My pressure reading shows the system is full. There are no visible leaks. Air blows hard, but is no longer cold. All the fuses are still good. The clutch engages. I pulled the AC Relay to test it per the FSM page G-57. The instruction say their should be no continuity betweent C & D. There isn't. But there is also no continuity to A & B, either. Is the relay bad? Any other ideas?

 

I just noticed a strange sound from the passenger's side while in the cabin. Isn't there a switch behind the glove box?

 

Post the high and low side readings, plus the ambient temperature and engine speed the readings were taken at.

What refrigerant is in the system? R-12? If so, what do you see in the sightglass when the compressor is running?

Is the suction line from the evaporator to the compressor cold?

 

You answered your own question. Sounds like the relay is just fine since the clutch engages....unless the clutch is engaged all the time in which case the relay is stuck shut....but that wouldn't preclude cold air from coming out of the vents.

 

R-12 is in the system. I used an R-134 gauge, since that is all I can get a hold of. The reading was just in the red on the low side, so that would be 65psi. I'll take a reading from the high side next time I get a chance.

The sightglass is clear. No bubbles.

Everything was done at a 800rpm ish idle. Ambient temp is about 80 F. I'll go back out and get a high side reading.

I also did a continuity check on the thermoswitch. It checked good. The cooling unit wouldn't fail to work unless it had a rupture, right?

 

The high side adapter doesn't fit. I'll have to find something else in town or order an R-12 gauge set to get a reading.

 

You had 65psi on the low side? That's too high. If that is accurate then your expansion valve could be stuck open, and flooding the evaporator with too much liquid which means the compressor is probably getting slugged with liquid, which doesn't make it very happy since liquids don't compress.

Then your charge is probably OK.

You're supposed to check the pressures at 1500 RPM.

If the compressor is running (you said it was earlier) then the thermoswitch is more than likely working just fine.

I'm not sure I understand what you're saying/asking.

Since it seems like you're OK on charge and your compressor is running, I'm wondering if you don't have a problem with one of the flaps under the dash that controls where the air goes. It may be that it is mixing hot air from the heater core in with cold air from the evaporator giving you warm/hot air at the vents.

 

That would be my luck. I'll remove the dash tomorrow. By the cooling unit I was referring to the big box behind the glove box that has the thermo switch attached. I think it is for the most part fins in a box.

Your hypothesis of the flaps being stuck is rather probable since I rarely use AC. The only reason I wanted it on was to get me to an interview dressed and pressed without sweating. My daily driver doesn't even have a compressor. I think it has been over a year since I used it. Thanks for the suggestion.

 

Before you haul off and remove the dash, you can test to see if the flaps are stuck on heat by pinching the coolant hoses that carry hot coolant to the heater core. You could also just let the car cool down completely then start it up and fire up the A/C and see if you get cold air...if the engine isn't hot then you can't get any hot air out of the heater.

If that 65psi on the low side is correct then you may be looking at a stuck expansion valve and not a flap problem.

 

Please let me know what is the outcome as i have the same problem with u. I just refilled the gas. The air is not cold when it blew out most of the time. When there is rattling sound under the glove box the air started to be blowing cold. And sometimes when I open my wastegate only the air cond starts to blow cool air. I check with some mechanic and they say is the compressor that fail. But i am sure the air cond only works when there is rattling sound behind the glove box.

 

Still just regular air when the AC is on at start up. When she's warm, the hot blows like fire. Should I replace the drier along with the expansion valve and o rings? I'd like this to be the first and last time I open up the AC. With the gauges and parts I need to do this I'll be paying a small fortune. Still beats having one of the retard mechanics tell me it's the compressor and have the same problem a thousand dollars later. I'll order the gauges to get the high side reading just to be sure (I'll need them to hook up the vaccum anyway). Five years of FD ownership is making my hair gray.

 

Yes...replace the drier when you have the system open. Be sure you get a real vacuum pump and not one of the el-cheapo venturi kind. Those won't draw enough vacuum to boil the moisture in the system away. I bought a little 2 stage Dosivac unit new on eBay for under $100.

ackits.com has some parts listed for our cars, and the prices seem to be quite good. I suggest that you call them before ordering to make sure you're getting the right parts...they have some incorrect pictures displayed on their site for various years of the RX-7.

 

Finally got my gauge set in.
Low-around 70 psi
High-about 73 psi

can't find a cold frost encrusted line under the hood. Any other possiblities besides the expansion valve?

 

Sure. Compressor not running..

 

I can see the compressor click on and off as the AC is turned on and off.

 

Well...if the compressor is spinning then either the compressor isn't compressing, or the expansion valve is shot...although I'm not sure an expansion valve at full open can flow enough to result in that low of a pressure differential between high and low. If you grab the hub of the compressor (the part that spins when the clutch is engaged) is it easy or difficult to turn? Does it turn smoothly?

 

I'm assuming you mean with the belt off. I'll try that next time I'm in the garage.

 

No...the pulley that the belt goes on should spin freely if the clutch isn't energized.

I mean grab ahold of the hub (the thing that spins when the clutch is energized) and see how hard it is to turn.

 

The evaporator thermoswitch on the FD is a known failure point. There are several other threads that talk about this. Pull the glove box & jumper the stat out to test; it's easy. Equal high & low side pressures indicate that the clutch isn't engaging.

 

either your compressors not running, or your compressor is toast. no way those pressures should be that close.