1991 ac problems
Thread Starter
2nd Gear
Joined: Jun 2015
Posts: 2
Likes: 0
From: Nixa Missouri
1991 ac problems
I have checked the system and it is full of Freon, there is power to the fuses , and out of the fuses but no power out to the compressor. When I turn the ac on the light flashes for a couple of minutes before it settles on whatever function you have pushed on the controller. Is the ac and heat controller bad?
Racer
Joined: Mar 2015
Posts: 492
Likes: 40
From: SE Ohio
St. Jude Donor '16-'17-'18,'19
There is a A/C interrupt relay that shuts off the compressor when you start the car. I'd check that first but its hard to get to. Located under the dash on the left side of the steering column. There are two relays under there, one for the starter interrupt the other for A/C. The one you want should be closer to the column. The starter relay wires are larger (maybe yellow).
May not be the problem but I hope it helps.
Pa
May not be the problem but I hope it helps.
Pa
Last edited by Pa'svette; Jun 18, 2015 at 01:11 PM.
Racer
Joined: Mar 2015
Posts: 492
Likes: 40
From: SE Ohio
St. Jude Donor '16-'17-'18,'19
That switch went bad on my pick/up a while back. With the air on and in drive it wouldn't idle.
Pa
Advanced
Joined: Dec 2006
Posts: 72
Likes: 0
How do you know it is full of freon? Without the compressor clutch engaged you can't see the high and low pressure. I don't know what go/no go the switch is looking for. The switch will not allow clutch to engage when freon is low. This is to protect your compressor. Look at the front of your compressor and hose connections. If you find black oily crud you have a leak. If on front of compressor the seal is leaking, plan to replace soon.
I have not looked at my 94, you should be able to jumper out the switch and force the clutch to engage. Do this only for info and don't run for longer than trouble shooting. If this engages the clutch add freon.
The system is pure pressure dp. If you checked pressure my depressing the freon valve you will only know that pressure is not equalized.
I have not looked at my 94, you should be able to jumper out the switch and force the clutch to engage. Do this only for info and don't run for longer than trouble shooting. If this engages the clutch add freon.
The system is pure pressure dp. If you checked pressure my depressing the freon valve you will only know that pressure is not equalized.
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
This is the low pressure switch. If the system is empty or low on freon it will not allow the compressor to engage:
To check for this as a problem, unplug the switch and jumper the contacts inside the connector. If the compressor engages (engine does not have to be running), then you have low or no freon in the system.
To check for this as a problem, unplug the switch and jumper the contacts inside the connector. If the compressor engages (engine does not have to be running), then you have low or no freon in the system.
Melting Slicks
Joined: Aug 1999
Posts: 2,240
Likes: 42
From: Baltimore, MD USA
I have checked the system and it is full of Freon, there is power to the fuses , and out of the fuses but no power out to the compressor. When I turn the ac on the light flashes for a couple of minutes before it settles on whatever function you have pushed on the controller. Is the ac and heat controller bad?
Pull the HVAC codes by doing the following.
Turn the ignition On.
At the same time press and hold the fan UP and Down switches until you see - 00 in the
LCD display.
Release the two switches.
Press the Auto Fan button once which will display what's stored in Parameter 00.
In your case you will probably see 09 which indicates the AC Programmer has disabled the compressor clutch from engaging due to the clutch cycling to many times in a given time frame. This usually is caused by low refrigerant .
To reset the system you disconnect the negative battery cable for a few seconds then reattach the battery cable.
When you turn the ignition On, the AC Programmer will recalibrate the blend door position. Takes about 30 seconds. When it's done the Blower motor comes on.
The AC clutch should now engage but the Programmer will disable the clutch again if the compressor cycles to many times over a certain time frame.
Last edited by Hooked on Vettes; Jun 19, 2015 at 09:55 AM.
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