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Discussion Starter #1
My AC stopped working couple months ago. It was ok in winter, now I want it back. The other day I opened the hood to poke around and discovered that my coolant temp sensor was broke at the top, like I took a hummer to it or something.

I replaced the sensor. Right after replacing it, my AC worked for about 15 minutes, then as car got hot it started blowing hot air again! I let the car cool since, and tried it again, still blows hot air.

My question is: Why did it start working? What could have caused it to start to work? And why the hell did it stop?


Anyways. I touched my upper radiator hose, and it was very hot, I'd say above 210F. I followed advice in the book and replaced the t-stat. I used stant 180F t-stat, plus new o-ring. The engine now operates cooler, and my fake temp gage is 1/3 bellow the half. Half is where it used to be before. I drove for an hour, temp gage never went to anything above that.


What do you think is going on here? Why won't AC work? It did worked fine for 15 min when I replaced damaged coolant temp sensor.


It appears that AC system is "good", it just doesn't engage the freaking clutch! Reference voltage for coolant sensor is 4.6 to 4.7 volts. Battery? Volt guage shows normal, car starts excellent. (before sensor and t-stat car used to have hard time starting when hot)

Please help.



Fernando
 

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I read through the section regarding this in the 1997 Service Manual. There's several possibilities as to why the A/C won't work, the simplest being that a 10A fuse in the fuse panel is blown, or is blowing. Other possibilities include:

Constant control relay module damaged.
Circuitry short/open.
A/C cycling switch damaged.
A/C system discharged/low charge.
A/C control damaged
Restricted A/C evaporator core orifice.
Low refrigerant level.
Inoperative A/C cycling switch.
Damaged A/C cycling switch.
A/C-heater function selector switch damaged.

Please note that this list is a conglomerate of the general A/C service, SATC A/C service, and Manual A/C service lists of possibilities.

Keep us posted if you need additional information.
 

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Discussion Starter #3
I messed with pressure switch today. I removed harness, and jumpered the connector. Clutch engaged, accumulator got really cold, cold air start blowing. :ztoohot: How do I test the pressure switch? So that I don't waste money in case it's perfectly good.


Thanks in advance,



Fernando

P.S. It looks after all I'm going to have my AC for the summer. I'm looking forward to clean sweat free cloth and no bad odor. :D
 

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Discussion Starter #5
UPDATE: Replaced cycle pressure switch, and added some refrigerant. Now it works ok.


Air blows cold and nice, but even on full fan power it doesn't blow good enough. At minimum fan power the only way to feel cold air is to put your hand close to air ducts. What do I check now?


I want to thank IronChopz for the info. It help me out just in the right itme. Thanks.



Fernando
 

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fastback777 said:
UPDATE: Replaced cycle pressure switch, and added some refrigerant. Now it works ok.


Air blows cold and nice, but even on full fan power it doesn't blow good enough. At minimum fan power the only way to feel cold air is to put your hand close to air ducts. What do I check now?


I want to thank IronChopz for the info. It help me out just in the right itme. Thanks.



Fernando
You're welcome! Question: do you mean that the air flow is insufficient, or that the amount of cooling is insufficient?

If fan speed is insufficient, I'd suspect the blower control (a small black box connected to the blower motor behind the glove box).

If the amount of cooling is insufficient, I'd doublecheck the pressure in the A/C lines. Do you have an A/C pressure gauge you can test with? Doublecheck the pressure to make sure it's in the correct range. I experienced an insufficient cold air flow before (much like you described), and tested the pressure. The needle registered at the bottom end of the "OK" range, despite using a can of R134a a few minutes before. Another can did the trick. If the pressure reads well into the OK range, there may be an imbalance of R134a-to-refrigerant oil.

Another possibility: the orifice tube may have become clogged. Replacing the orifice tube will alleviated that problem.

If anything, you can have an A/C tech evacuate the system, and recharge it (or recharge it yourself). It's the time of year in which various shops may be running A/C specials...
 
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