Is there anything electrical that could cause the AC compressor to not engage? - Chevy Impala SS Forum
 1Likes
Reply
 
LinkBack Thread Tools Display Modes
post #1 of 26 (permalink) Old 09-02-2018, 11:20 PM Thread Starter
TGO
Senior Member
 
Join Date: Sep 2012
Location: Staten Island, NY
Posts: 1,695
 
Is there anything electrical that could cause the AC compressor to not engage?

AC worked fine all summer. Has worked fine for 3-4 summers. It worked fine today. Drove somewhere, parked...shut the car off then remembered I didn't turn off the AC so I switched the knob to the off position with the car off. I don't like starting the car with the AC on. Went in to the BBQ, came out tonight and started the car and turned on the AC and nothing. The compressor doesn't come on.

I had a problem last year with the fan relay's popping due to old/worn out fans. I replaced the fans and the relay(s) and haven't had a problem since. I don't remember exactly but I'm pretty sure the AC did work even with a burned out fan relay. Just the car would overheat very fast in traffic.

So, it's gonna be in the 90's again this week and my mechanic is closed for vacation so I'm hoping it could be a fuse or relay or something I can fix easily by myself. I've had a catastrophic failure of the compressor before and the instant discharge of refrigerant was quite dramatic. That definitely did not happen. Though I'm afraid the headers might have finally burned a pinhole in the ac lines and the system just slowly discharged while parked today. AC lines are bent away from the headers for clearance and wrapped in that heat wrap material. But still that seems the most obvious problem.

2001 Corvette ZO6
1995 Impala SS - H/C/I - BBB
TGO is offline  
Sponsored Links
Advertisement
 
post #2 of 26 (permalink) Old 09-03-2018, 07:29 AM
Senior Member
 
gbhs72's Avatar
 
Join Date: Nov 2015
Location: Lawton, Ok
Posts: 1,473
 
Just a quickie. I would think the first thing to check would be, is the clutch engaging? I'm just learning about the AC. I would get one of those cans with the valve installed @ the parts store and hook it up if it is coming on. Then maybe you could find out if you have a leak. I'm sure more answers will follow. Until you find out for sure. Stay cool.


Mark: Snowman-33

93 9C1: Work & Cubic Ca$h This started with a new headlight and fender Celeritas In Conficiendo
gbhs72 is offline  
post #3 of 26 (permalink) Old 09-03-2018, 12:29 PM Thread Starter
TGO
Senior Member
 
Join Date: Sep 2012
Location: Staten Island, NY
Posts: 1,695
 
No the clutch doesn't engage and so the compressor doesn't come on.

I kind of remember reading about a way to force it to engage for testing? Idk..

2001 Corvette ZO6
1995 Impala SS - H/C/I - BBB
TGO is offline  
 
post #4 of 26 (permalink) Old 09-03-2018, 01:14 PM
Senior Member
 
Jimpala95's Avatar
 
Join Date: Oct 2005
Location: Chicagoland
Posts: 587
 
Garage
Hello TGO, Yes there is electrical that will keep a charged system from working and compressor from engaging.In the underhood elect center......Check the A/C compressor relay and the fuse(#7) that feeds it.


Jim
Jimpala95 is offline  
post #5 of 26 (permalink) Old 09-03-2018, 01:15 PM
Senior Member
 
Jimpala95's Avatar
 
Join Date: Oct 2005
Location: Chicagoland
Posts: 587
 
Garage
Here's a pic I took from from my 96 serv manual if it helps.
Jim
Attached Thumbnails
Click image for larger version

Name:	`.jpg
Views:	70
Size:	370.0 KB
ID:	179538  

Jimpala95 is offline  
post #6 of 26 (permalink) Old 09-03-2018, 02:21 PM Thread Starter
TGO
Senior Member
 
Join Date: Sep 2012
Location: Staten Island, NY
Posts: 1,695
 
I was just out there looking at the relay(s). They look fine to me. What that means is I don't see any "heat" on them. When my fans were bad the relay basically melted. The prongs turned blue-ish, etc. I don't see any of that. I didn't check the fuse though I'll have to do that.

I also pulled the temp sensor with the car running and both my fans came on.

I felt around the ac lines where they go under the header. I don't feel any oil on the lines themselves. They feel and look dry. I'm not sure if the header heat wrap that's around them would absorb all that would have leaked out. Still my gut is telling me that that's the problem. I suppose all the refrigerant wouldn't have to leak out, just enough to get a low pressure reading and stop the compressor from working.

2001 Corvette ZO6
1995 Impala SS - H/C/I - BBB
TGO is offline  
post #7 of 26 (permalink) Old 09-03-2018, 09:36 PM
Senior Member
 
Join Date: Mar 2002
Location: Plano, Texas
Posts: 581
 
On the side of the Receiver/Drier there is a pressure switch. When the Freon gets low, this switch prevents the compressor clutch from engaging.

Simple test: unplug the harness and use a piece of wire and jump across the slots in the plug. This is just temporary to see if the relay and clutch works. You will need to have the engine running with the A/C set to on.
When you jump across the slots in the plug, the compressor should engage. If the clutch engages, then either the Freon level is low or the pressure switch is bad.

My pressure switch failed a few years ago. The switch is easy to replace as the switch just unscrews.

Later,
Michael

2012 Best of ISSCA; 2013 ISSCA Nats FTD Autocross and Road Racing
1995 BBB: - ERE383 #74 516 FWHP/526 FWTQ
1984 Monte Carlo SS 12.8 @ 104
2005 GTO M6 357.7 RWHP and 358.8 RWTQ PCMFORLESS
madamorr is offline  
post #8 of 26 (permalink) Old 09-03-2018, 09:45 PM Thread Starter
TGO
Senior Member
 
Join Date: Sep 2012
Location: Staten Island, NY
Posts: 1,695
 
I believe the pressure switch is new-ish. When I first got the car it was november 2012...no need for AC then but the following summer I had the system serviced. I tried charging it myself which worked for a little while but there were multiple leaks. I took it to a shop and they replaced the compressor and they said there was a leak at the pressure switch so they changed that as well.

IDK the quality of the part they put in there...I suppose it's entirely possible that it failed.

If I jump the switch and the compressor comes on...will the AC blow cold is there is low pressure? Is there any other way to tell if the pressure is low other than putting gauges on it? It's really hard to believe the car was blowing ice cold when I drove it and only a few hours later the AC doesn't work at all.

Also, fuse #7 is for the primary cooling fan so since both fans work the fuse is ok.

2001 Corvette ZO6
1995 Impala SS - H/C/I - BBB
TGO is offline  
post #9 of 26 (permalink) Old 09-03-2018, 09:56 PM
Senior Member
 
Join Date: Mar 2002
Location: Plano, Texas
Posts: 581
 
If you jump across the plug and the compressor comes on, the AIR may or may not blow cold depending how low the system may be.

My pressure switch was also leaking, so I replaced the o-ring and no more leak.

The gauges are fairly inexpensive from local parts stores.

As your car is a 1995, you have R134a Freon which is still available without a license and fairly reasonable in price. My local Sam's club was selling cases of 12 cans for $30. I purchase 6 cases to have around for future use.

Later,
Michael

2012 Best of ISSCA; 2013 ISSCA Nats FTD Autocross and Road Racing
1995 BBB: - ERE383 #74 516 FWHP/526 FWTQ
1984 Monte Carlo SS 12.8 @ 104
2005 GTO M6 357.7 RWHP and 358.8 RWTQ PCMFORLESS
madamorr is offline  
post #10 of 26 (permalink) Old 09-03-2018, 10:12 PM
Senior Member
 
gbhs72's Avatar
 
Join Date: Nov 2015
Location: Lawton, Ok
Posts: 1,473
 
TGO, I checked and there are a bunch of O'reilly stores on Staten Island. Might want to borrow one of these. https://www.oreillyauto.com/detail/b...q=rental&pos=1

Mark: Snowman-33

93 9C1: Work & Cubic Ca$h This started with a new headlight and fender Celeritas In Conficiendo
gbhs72 is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Chevy Impala SS Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome