1992 Toyota Camry A/C Woes

[the_professional]

I finally found a reason to peek in.

This isn't a huge issue for me but, I'd rather I fix it. The Air Conditioning fails to work.

It's still on it's original R12 charge, & worked perfectly until last summer. I never went into diagnosing it because the car isn't used much & the Air Conditioner is never used by my mother.

We're at 75,000 miles at the moment on the old girl.

The Problem:

- When I press the A/C button, it certainly feels like the A/C clutch engages.

- I'm sure there is freon because the A/C light remains on, & IIRC it would flash if there was no freon.

- The condenser fan does not turn on.

- When at idle, both fans do come on when "hot".

Thanks In Advanced! I really appreciate it.

[AllanMn]

Sight glass?

[Mister_Perkins]

First off, you want to make sure that the AC compressor clutch is actually engaging, and you also want to check the amount of freon in the system using manifold gauges or a Low Side / High side gauges. Monitor both sides, low and high.

If the low side is very low, your probably leaking coolant somewhere. If the low and high side is very high, you probably have blockage .. most likely in the Evaporator somewhere. If the high side is Bouncing with the RPM (fluctuating) Rev the motor up and see if it fluctuates more. If it does, the compressor is probably bad.

Pull the AC Fuse and jump the junction block with a paperclip. See if the fans turn on. If they do, check the A/C inside the car and see if its cold. If not, but you hear/see the compressor kick on, go to the High side while the car running and look into the sight glass and check to see if you can see liquid moving. (Right infront of the battery).

If the Air conditioning is still not cold, but the compressor is kicking on, unplug the high pressure switch and put a jumper into the Pigtail (Plug) and see if the A/C Gets cold. If it does, replace the high pressure switch.

Keep in mind, on older vehicles the O-Rings go bad a lot, evacuating the freon. Most common place for it to pass by the o-ring is the expansion valve. This is a $30.00 part, and the job of it is to limit the amount of freon that passes through the system. They go bad a lot, and are a common point of Freon leaks.

Edit:

Heres a chart to help you out in your diagnostics:

Manifold Pressures:

Low Side | high side | Duct Temp | Possible Cause
Low----------Low--------Warm-------Low Refrigeration Charge
High--------High--------Warm-------Overcharge of refrigeration
High--------high-------somecool----Air in system or overcharge
Normal-----Normal-------Warm-------Moisture in the system
Low---------low---------warm-------expansion valve stuck closed
low---------low---------warm-------orfice tube plugged
low---------low---------warm-------high side restriction
high--------low---------warm-------compressor or control valve failed

[Stillrunning]

the_professional(?), Perkins is correct to say first you need to determine IF the A/C clutch is engaging. Look at the clutch pulley when the A/C switch is on and off (fan switch on) and you'll see if the rear of the pulley/clutch is spinning or not. Also make sure that the clutch engages with the fan switch off and on(with A/C switch on). Don't worry about pressures unless you have the proper equipment and you know what you're looking at. If the clutch is engaging are you getting any cooling (fan off)? If you're getting some cooling then I'd pursue an electrical problem with the fan circuit. You can use a household fan to blow air across the condenser to see if you get cooler A/C air or you can also disconnect the A/C fan plug and jump the connectors to the battery to see if you get cool(er) air with the fan running directly.

If the clutch is engaging (means there's enough pressure to engage) then it may be an A/C fan relay. Under the hood on the driver's side closest to the firewall is an A/C relay box. Inside will be the clutch relay(closest to firewall), cooling fan #2 and cooling fan #3 relay (you may not have the #3). If you have a #3 then switch it with #2 and see if the fan spins with A/C on. If no #3 then you'll need a relay circuit diagram (Haynes manual) to know which contacts to jump to see if the fan engages, but you can also just buy a new relay and switch it with #2 & #3 to see if the fan works.