940 1994 a/c

[billofdurham]

The best way to test the AC is whilst stationary. That is what the experts do because they always have their gauge set connected whilst running the checks and adding, or taking away, refrigerant. This also eliminates any fluctuation due to the speed of the vehicle. At highway speeds the AC doesn't usually have to work so hard because of the cooling effect of the air movement.

The Volvo method is:
Close the bonnet (hood) and doors.
Run the engine at 2000rpm.
Set the blower on third speed.
Set temp control to cool.
Select panel vent position on airflow mode.
Select recirculated air.
Open panel vents.
Put a thermometer in a centre vent.
Turn on AC.
After 5 - 10 minutes ensure compressor is cycling.
The duct temp should be 41 - 46F (5 - 8C) at an ambient temperature of 68 - 86F (20 - 30C) or 46 - 54F (8 - 12C) at an ambient temp of 104F (40C).

The temp differences you quote would appear to be acceptable as one expert has said, "The vent temperature should range from around 42-55 degrees in my experience." This did not just apply to Volvo cars.

As your checks were done whilst mobile there are several factors which could account for the difference between the Volvo and the Toyota - speed, amount of traffic, different airflow characteristics across the condensor and so on.

If the compressor is cycling normally and not making any weird noises it is probably OK. However, it can be checked quite easily by an AC tech who has the proper gauge set, that is two gauges which read low and high pressures simultaneously. If the low pressure is too high and the high pressure too low it is an indication of a compressor starting to fail as it is not pumping enough. A less common fault is a compressor clutch slipping but this is usually accompanied by a chirp or a squeal. Of course the drive belt may need adjusting!

Bill.

[joooro]

There is no relay for the air conditioning.

Where, and how, are you testing for power?

Bill.

I checked the fuse and checked power to the low limit switch...I pulled the plug of and check to see if there was voltage to the lowlimit switch...i did not get a reading there... I should have , right...?

[billofdurham]

Did you miss something out?

Bill.

[joooro]

Still working on my 1994 940 A/C.. I pulled the fuse panel out and checked with a tester and the light did not light up. I checked the back of panel and did not see any burnt wires or loose wires... So , I am guessing that I have no power to fuse box , which is # 6 on panel...it is also #18 I believe , but I am getting power to that fuse.....any ideas? Thanks

[vegasjetskier]

Still working on my 1994 940 A/C.. I pulled the fuse panel out and checked with a tester and the light did not light up. I checked the back of panel and did not see any burnt wires or loose wires... So , I am guessing that I have no power to fuse box , which is # 6 on panel...it is also #18 I believe , but I am getting power to that fuse.....any ideas? Thanks

So #6 has no power?

Does #16 or 21?

[billofdurham]

#18 is the high beam (right).

#16 is the blower - climate control as is #6. However, the wiring diagram I have only shows #16 in use.

Bill.