no ac help
Melting Slicks
Joined: Jun 1999
Posts: 2,931
Likes: 127
From: Ashland Alabama
That's kind of hard to diagnose with what you posted.
It could be out of Freon.
Bad low pressure switch.
Bad high pressure switch.
etc.
Does the compressor come on when you turn the a/c on?
It could be out of Freon.
Bad low pressure switch.
Bad high pressure switch.
etc.
Does the compressor come on when you turn the a/c on?
Thread Starter
Heel & Toe
Joined: Mar 2015
Posts: 24
Likes: 0
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
You must have enough refrigerant in the system to turn on the low pressure switch to get the compressor to engage. It's possible that the low pressure switch is bad. You can test for a low pressure switch problem by unplugging it and jumpering across the connector pins. The engine does not have to be running, just turn on the AC and the ignition. The compressor clutch should click (quite loudly) when the low pressure switch is jumped (assuming everything else is OK).
I understand that later years have a relay to turn on the compressor (I have an earlier car that does it through the blower control module). Is the relay OK?
The "A/C" fuse is for the compressor -- is that OK?
I understand that later years have a relay to turn on the compressor (I have an earlier car that does it through the blower control module). Is the relay OK?
The "A/C" fuse is for the compressor -- is that OK?
Last edited by Cliff Harris; Mar 27, 2015 at 11:56 PM.
Thread Starter
Heel & Toe
Joined: Mar 2015
Posts: 24
Likes: 0
You must have enough refrigerant in the system to turn on the low pressure switch to get the compressor to engage. It's possible that the low pressure switch is bad. You can test for a low pressure switch problem by unplugging it and jumpering across the connector pins. The engine does not have to be running, just turn on the AC and the ignition. The compressor clutch should click (quite loudly) when the low pressure switch is jumped (assuming everything else is OK).
I understand that later years have a relay to turn on the compressor (I have an earlier car that does it through the blower control module). Is the relay OK?
The "AC" fuse is for the compressor -- is that OK?
I understand that later years have a relay to turn on the compressor (I have an earlier car that does it through the blower control module). Is the relay OK?
The "AC" fuse is for the compressor -- is that OK?
Race Director
Joined: Sep 2001
Posts: 10,560
Likes: 439
From: Wellington, FL
St. Jude Donor '11 thru '25
Melting Slicks
Joined: Jun 1999
Posts: 2,931
Likes: 127
From: Ashland Alabama
As mentioned testing the compressor for power is a good idea. I used to rule that out and hunt elsewhere first but I actually had a bad clutch once. They wanted $279 for the clutch and $135 for a new compressor WITH the clutch. I remember when you could by the clutch assembly for $35 for most of them.
Anyways as mentioned the electro magnet clutch can go out itself and the clutch plates can wear down so far that with age it cant pull the plate to engage the clutch. So checking for power there is a good idea.
If the clutch doesn't have power and jumping the low pressure switch doesn't engage it then normally theres a blown fuse or a bad controller on fancier a/c control units.
Anyways as mentioned the electro magnet clutch can go out itself and the clutch plates can wear down so far that with age it cant pull the plate to engage the clutch. So checking for power there is a good idea.
If the clutch doesn't have power and jumping the low pressure switch doesn't engage it then normally theres a blown fuse or a bad controller on fancier a/c control units.
Thread Starter
Heel & Toe
Joined: Mar 2015
Posts: 24
Likes: 0
As mentioned testing the compressor for power is a good idea. I used to rule that out and hunt elsewhere first but I actually had a bad clutch once. They wanted $279 for the clutch and $135 for a new compressor WITH the clutch. I remember when you could by the clutch assembly for $35 for most of them.
Anyways as mentioned the electro magnet clutch can go out itself and the clutch plates can wear down so far that with age it cant pull the plate to engage the clutch. So checking for power there is a good idea.
If the clutch doesn't have power and jumping the low pressure switch doesn't engage it then normally theres a blown fuse or a bad controller on fancier a/c control units.
Anyways as mentioned the electro magnet clutch can go out itself and the clutch plates can wear down so far that with age it cant pull the plate to engage the clutch. So checking for power there is a good idea.
If the clutch doesn't have power and jumping the low pressure switch doesn't engage it then normally theres a blown fuse or a bad controller on fancier a/c control units.
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Melting Slicks
Joined: Jun 1999
Posts: 2,931
Likes: 127
From: Ashland Alabama
Fuse feeds climate control in car.
Climate control feeds power to the high pressure switch.
High pressure switch feeds power to the low pressure switch.
Low pressure switch sends power to compressor.
According the shop manual
So if low pressure switch has no juice on either wire then check the high pressure switch.
If the high pressure switch doesn't have power and the fuse isn't blown the problems in the climate control inside.
Climate control feeds power to the high pressure switch.
High pressure switch feeds power to the low pressure switch.
Low pressure switch sends power to compressor.
According the shop manual
So if low pressure switch has no juice on either wire then check the high pressure switch.
If the high pressure switch doesn't have power and the fuse isn't blown the problems in the climate control inside.
Thread Starter
Heel & Toe
Joined: Mar 2015
Posts: 24
Likes: 0
As mentioned testing the compressor for power is a good idea. I used to rule that out and hunt elsewhere first but I actually had a bad clutch once. They wanted $279 for the clutch and $135 for a new compressor WITH the clutch. I remember when you could by the clutch assembly for $35 for most of them.
Anyways as mentioned the electro magnet clutch can go out itself and the clutch plates can wear down so far that with age it cant pull the plate to engage the clutch. So checking for power there is a good idea.
If the clutch doesn't have power and jumping the low pressure switch doesn't engage it then normally theres a blown fuse or a bad controller on fancier a/c control units.
Anyways as mentioned the electro magnet clutch can go out itself and the clutch plates can wear down so far that with age it cant pull the plate to engage the clutch. So checking for power there is a good idea.
If the clutch doesn't have power and jumping the low pressure switch doesn't engage it then normally theres a blown fuse or a bad controller on fancier a/c control units.
Melting Slicks
Joined: Jun 1999
Posts: 2,931
Likes: 127
From: Ashland Alabama
Well a bad low pressure switch could cause that or its low on Freon. If you can jumper the low pressure switch and it cools fine aka nice and cold then it probably is fine on the Freon level just a bad switch.
Race Director
Joined: Sep 2001
Posts: 10,560
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From: Wellington, FL
St. Jude Donor '11 thru '25
Melting Slicks
Joined: Jun 1999
Posts: 2,931
Likes: 127
From: Ashland Alabama
Race Director
Joined: Mar 2015
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Yes just a gusse but the fill scharder valve is old and needs to be replaced and can be done without losing your charge and the low freon will keep it from working easy test is take the cap off spite on your finger and fill the hole and look for bubbles
Last edited by antfarmer2; Mar 28, 2015 at 11:50 AM.
Racer
Joined: Dec 2007
Posts: 416
Likes: 3
Say the system is fully charged and someone removes the schrader valve, they're going to get a face full of refrigerant and oil.
Yes, it can be done with a tool designed to do it, like shown below. I dug that out of my tools that I never use box because when a schrader valve does leak it's either already out of refrigerant or the proper cap can be put on to seal it shut.
But money would be better spent on some means of checking pressure. Say like a gauge or something....
Melting Slicks
Joined: Aug 2008
Posts: 2,082
Likes: 50
From: Palmdale CA
I have seen and read too many times were a guy has overcharged his system by Guessing, I have also seen and read were a guy replaces his safety/operational switch's while in fact he was low on "Gas"
I don't agree with "Shorting" switch's in order to trouble shoot, if your switch communicates with the ECM/PCM You could introduce an ESD event/transient into the computer..
Always use an high impedance meter and proceed with caution, other wise a simple problem becomes a much larger problem..