89 Camry-4cyl A/C not working

[gacamryowner]

My 89 Camry 4 cyl A/C quit working for about 3 weeks now. The dashboard switch flickered on/off several month before it went out. The compressor is 1 year old with full freon, new alternator, good fuses and relay. I took it to a mechanics who ran a diagnostic test and determined that its something going on with the A/C amplifier. I went to a junkyard and got several A/C amplifier along with some condenser amplifier. put them on, nothing works. I tried some dashboard A/C switches and still does not work. What should I do? If anyone can help, please post or call 404-483-4829. Much thanks!

[Brian R.]

Check your pressure switch (on receiver) for correct function. Should have continuity between terminals 1 and 4 (two opposed and closest together, 1 is near post) with correct pressure.

Check your A/C fan and clutch relays for correct function.

Check your condensor fan for operation, should draw 5-8 Amps and run freely when battery current is connected.

Check magnetic clutch function. Should energize when connected to battery current.

Check evaporator temperature sensor. Resistance should be 4.6 - 5.1 kOhms in ice water and 2.1 - 2.6 kOhms at 59 degrees F.

Check revolution detecting sensor (compressor) for resistance. Resistance should be 160 - 210 Ohms at 68 degrees F.

Expansion valve?

Compressor? Freon fill? Are you sure?

[gacamryowner]

Thanks Brian! I will try some of your advices today.
Can you put your advice in layman's terms. Where is the pressure switch? Which receiver are you referring to? How do I check it? What about the diagnosis given by the mechanic that there is something wrong with the AC amplifier? Should I take my Camry to another mechanic? He quoted me $400 to fix the a/c with a new ac amplifier. Please advice! Thanks in advance!

[Brian R.]

Pressure switch cuts off A/C compressor when internal pressure falls too low because of insufficient freon. If you are sure you have enough freon charged, then the pressure switch should have continuity (0 resistance). Check with ohmeter. It is on the receiver, a small can-shaped tank with a sight glass on top. Just follow the compressor lines. If the pressure switch has high resistance, then it is defective and needs to be replaced. If it is not fuctioning, then your system thinks you are low on freon, no matter how much you have in it.

If you replaced the A/C amplifier with others and it still didn't work, it is not likely to be the only problem. Check the other functions I mendioned first.

If you have to rely on a mechanic, I would bring it to the dealer and get it done right (if they are competent). See if you can find a competent dealer.

[gacamryowner]

Thanks again Brian. I still can't find the pressure switch on my 89 camry. I see it on the picture in Haynes repair manual, but, I can't find it in the 89 model. Is it next to a landmark part. In the meantime, I'll keep looking.
I also seem to remember the mechanic said that the problem is that the signal from the switch on the dashboard is not getting through to the compressor to kick it on. Do you know how do I go about checking it? I went to the junkyard and found several A/C switches and tried each one on to no avail. Do I need to take the dashboard out to test the connection from the switch to the hardware behind the dashboard?
The mechanic also said that if there is way to just put a switch on the dashboard that control the compressor, it would be a cheap way to fix it. But to remember turn it off. Do you know how to do that?
In the meantime, I will keep checking. Thanks again!

[Brian R.]

I am not sure of the location of the pressure switch in your vehicle. Normally, it's on the top of the receiver, but it could be anywhere in the high-pressure circuit (between the compressor and the condensor).

Many things could keep the switch signal from reaching the compressor. Most of the ones I suggested checking fall directly or indirectly in that category.

Don't install a bypass switch, fix the problem you have. The safety cut-offs in the system are there for a reason. If you bypass them, you stand a good chance of trashing your compressor.

If you have replaced the dashboard switch, then it is not the problem. The wiring is one of the least likely areas to cause you a problem, although possible.

Your mechanic may be trying to do you a favor, but if he can't fix the problem you have, find someone who can.

[ProMan]

If the switch led flashes immediately when you turn the AC on and the AC doesn't work at all, then it could be some electronic or electric problems. If it flashes some time (20 seconds or so) after you turn AC on and you do feel some cold air coming out, then there is something wrong with the pressure of the freon.

You can check if the clutch works. Look at the pulley of the compressor when the engine is running and the AC is off. The center part (the clutch) of the pulley should not turn with the pulley. Now turn on the AC, the clutch now should turn with the pulley. If it's not turning, it could be the clutch or the wiring. If it's operating normally, then, could be your pressure switch, or incorrect amount of freon in the system.

[gacamryowner]

Thanks Brian and Proman. I located the 10amp fuse on the right kick panel and was blown. I put a new one in and was also blown after traveling or idling when the compressor kicks on. The A/C runs about a while then quits after the fuse is blown. Any suggestions as to what the problem might be? Could it be a tight alternator? Please help!

[Brian R.]

No, not a tight alternator. You either have a short in the wiring for generator/clutch/fan power or the generator/clutch/fan is pulling too many amps because of an internal defect/short.

See if the A/C fan (behind the radiator) turns freely by hand. Then see if it runs when batter current is connected to it. Measure the amps drawn and compare to the numbers I gave above. If the fan is good and not drawing too many amps, then it may be that your compressor is damaged and needs to be replaced.

Since this is expensive, I would bring it to a reputable mechanic and have him diagnose it. Internet troubleshooting is at best hit and miss.

[gacamryowner]

I put in a new A/C amplifier and changed the fuse. Its working well so far (knock on wood!) AC works fine when the Camry is running. But when the days heat up around noon. the AC take a while to get cool especially when I idle at the light. Do I need more freon? What else can I do to protect my AC and make it run well?