A/C Troubles. need advice

irishpwr46 · Sep 23, 2011

so i drove to the gym today. it was raining pretty bad. had my defog on with the A/C on the way to the gym. everything is running fine. get to the gym, workout, come back to car. still raining. go to turn on my A/C, but the compressor isnt coming on. is it possible that on my way to the gym, something got wet and burnt out? all fan speeds and temp controls are working fine otherwise, but when i hit the A/C button, or when i put it on max A/C, the compressor doesnt engage. ideas? thanks in advance

94tbird · Sep 23, 2011

check the easy stuff first. no specific order.

A/C cycle switch, located drivers side engine bay towards the firewall. It is in one of the A/C lines
A/C power switch, located on the side of the compressor
Make sure there is R134a in the system. Its designed to not come on if the refrigerant is low
Check fuses

tmcolegr · Sep 23, 2011

what year vehicle?

irishpwr46 · Sep 23, 2011

08 gt all connections seem dry and tight. gonna have to take it to my mechanic to check the pressure.

94tbird · Sep 23, 2011

you can check it real quick by unplugging the ac cycle switch and jumping it with a wire or paper clip. It will turn on the compressor regardless of refrigerant. If it turns on, your looking at low refrigerant. If it doesn't, you may have a bad coil on the A/C compressor itself. Easily repaired.

irishpwr46 · Sep 23, 2011

^ill give that a shot

irishpwr46 · Sep 24, 2011

fucking thing started working again

irishpwr46 · Mar 28, 2012

not working again

michael.konor · Mar 29, 2012

I posted a schematic in the other thread about AC problems.

If you need any help, just PM me.

irishpwr46 · Jun 20, 2012

UPDATE: had my mechanic take a look. he can get the Clutch to engage when he grounds out circuit 85 in the fuse box. its a gray/white wire going back to the computer. he said its possible it needs a new computer. he told me to ask around before doing anything though.

michael.konor · Jun 21, 2012

In order for the computer to command the ground for the clutch to engage, it has to get the input/command from the enviromental control switches.

irishpwr46 · Jun 21, 2012

so it could be a cabin switch problem?

skwerl · Jun 21, 2012

You said it was raining. Do you have water intrusion at the SJB? I've heard all kinds of issues when that gets wet.

BruceH · Jun 21, 2012

It may just need charging. There is a pressure switch near the radiator on the drivers side. If there isn't enough pressure for the switch to make contact the clutch won't engage.

irishpwr46 · Jun 22, 2012

Pressure is ok, I had it checked. I'll have to look into the sjb. Does anyone know offhand if there's any ac relays in there

Sprayer84 · Jun 22, 2012

Does your mechanic have access to a diagnostic tool that will show him a data stream from the bcm? You need to see if it is even being commanded on when you use the dash controls. I wouldn't jump to conclusions about a bad computer yet.

michael.konor · Jun 22, 2012

irishpwr46 said:
Pressure is ok, I had it checked. I'll have to look into the sjb. Does anyone know offhand if there's any ac relays in there

Yes, there's a relay. Look on your manual in the fuse listing. It will.show them in that section.

TexasBlownV8 · Jun 22, 2012

Relays and fuses. The SJB has a fuse. BEC has a couple fuses plus the relay.
Do you have any DTCs, is the car running ok? The reason I ask is that power that feeds through the relay coil is provided by PCM relay #1, which also provides power to other circuits, including the O2 sensor heaters and other things.
I had a o2 sensor wire get shorted out and blow the fuse. It was the fuse right above the "1.0" black diode when standing over the BEC from the passenger side fender, next to the a/c relay.

irishpwr46 · Jul 30, 2013

So I took the car to ford. They recharged the system and said they were able to get the compressor to come on with a computer hooked up to it. They tried blaming my tune first. After that they said it was a bad ground and that I would probably have to get a new ecu and sjb. Any thoughts?

skwerl · Jul 30, 2013

Sounds like they are throwing parts/money at it hoping to fix it. Some shops have mechanics, most just have parts changers.

A/C Troubles. need advice

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