AC doesn't get cold until the engine fully warms up - LS1TECH - Camaro and Firebird Forum Discussion



General Maintenance & Repairs Leaks | Squeaks | Clunks | Rattles | Grinds

AC doesn't get cold until the engine fully warms up

Reply
 
Thread Tools Search this Thread
Old 03-18-2017, 01:25 AM   #1
TECH Apprentice
Thread Starter
iTrader: (1)
 
Join Date: Mar 2015
Location: College Station, TX
Posts: 347
Default AC doesn't get cold until the engine fully warms up

SOLVED, READ POST #12 FOR SOLUTION

Hi all, I'm having a really weird problem with my AC.

Immediately after I turn on the engine the AC will be cold and then it stops being cold after 20 or so seconds. It'll stay not cool until the engine fully heats up (you can see the temp drop several degrees from the thermostat opening) and then it'll suddenly start blowing cold air.

--The clutch electromagnet (OEM AC Delco) is only about 3-4 years old and it's not behaving like a weak coil, but I checked it to see it it was just too weak. During the time the air is lukewarm, the coil isn't even trying to engage as suggested by putting a screwdriver next to it. After the engine warms up, the clutch engages no problems. No slipping. And cycles just fine.

--Maybe a pressure sensor problem and the engine heating up warms the refrigerant lines to increase pressure enough to trip the sensor? Nope. Replaced both the high and low side sensors and nothing changed. OEM AC Delco parts.

--Refrigerant pressure is also normal.

When it starts working after the engine warms up, it's cold and stays cold. No problems. And if I turn the engine off and run a brief errand like a cup of coffee so that the engine is still hot when I get back, turn the engine back on and the AC is fine.

It's a '96 Chevy.

Last edited by coryforsenate; 04-10-2017 at 07:08 PM.
coryforsenate is offline   Reply With Quote
Old 03-18-2017, 06:14 AM   #2
TECH Senior Member
iTrader: (2)
 
Join Date: May 2008
Location: South Florida
Posts: 10,625
Default

Only thing I can think of.....electric fans may not be working until the engine gets hot and then the fans come on because the coolant is hot.......

.
LS6427 is offline   Reply With Quote
Old 03-18-2017, 01:22 PM   #3
Save the manuals!
iTrader: (5)
 
wssix99's Avatar
 
Join Date: Dec 2007
Location: Chicago, IL
Posts: 9,846
Default

Quote:
Originally Posted by coryforsenate View Post
It's a '96 Chevy.
Chevy what?


Quote:
Originally Posted by LS6427 View Post
Only thing I can think of.....electric fans may not be working until the engine gets hot and then the fans come on because the coolant is hot.......
+1. Your A/C needs the fans to pull air over the condenser and they should come on right away with the A/C or defogger.
wssix99 is offline   Reply With Quote
Old 03-30-2017, 08:23 PM   #4
TECH Apprentice
Thread Starter
iTrader: (1)
 
Join Date: Mar 2015
Location: College Station, TX
Posts: 347
Default

Sorry for the much delayed reply.

It's a '96 Chevy Silverado. There aren't electric fans, just the belt-driven one and it's working fine. The clutch is flat out not engaging or even trying (not a weak magnet), but once the engine runs for a bit it starts cycling like normal. I had a weak magnet a few years ago and replaced it. The signs are completely different than they were then.

Is there maybe a component of the compressor that's having problems?

The A/C system isn't that complicated. There's only a few parts that measure/sense or turn on/off. High/Low sensors, compressor, clutch magnet, fuses, and the dials in the cab, as far as I can think. But I'm at a loss for what would make the compressor cycle on/off when I first start up the engine, then stop for several minutes, and then start cycling normally for as long as I drive.
coryforsenate is offline   Reply With Quote
Old 04-05-2017, 05:29 PM   #5
TECH Apprentice
Thread Starter
iTrader: (1)
 
Join Date: Mar 2015
Location: College Station, TX
Posts: 347
Default

No takers? I agree it's a very difficult thing to diagnose.
coryforsenate is offline   Reply With Quote
Old 04-05-2017, 05:49 PM   #6
Save the manuals!
iTrader: (5)
 
wssix99's Avatar
 
Join Date: Dec 2007
Location: Chicago, IL
Posts: 9,846
Default

The A/C system on your truck probably also doesn't have a lot in common with most of the cars discussed on the site.
wssix99 is offline   Reply With Quote
Old 04-05-2017, 06:17 PM   #7
TECH Fanatic
 
Join Date: Mar 2013
Posts: 1,984
Default

Quote:
Originally Posted by coryforsenate View Post
No takers? I agree it's a very difficult thing to diagnose.
Actually it maybe quite simple, from here I suspect its just low on coolant. Either try adding a few ozs and see if it remys the problem OR put a set of gauges on it and watch the pressures. As the engine warms up the coolant in the AC expands and as it expands it comes up to enough pressure to activate the compressor. Good Luck
RockinWs6 is offline   Reply With Quote
Old 04-07-2017, 08:18 AM   #8
TECH Addict
iTrader: (14)
 
chrysler kid's Avatar
 
Join Date: Feb 2005
Location: Mckinney Plano Frisco
Posts: 2,545
Default

+1 for a weak fan clutch or fan shroud housing damage
chrysler kid is online now   Reply With Quote
Old 04-07-2017, 11:20 AM   #9
TECH Fanatic
 
Join Date: Mar 2013
Posts: 1,984
Default

Quote:
Originally Posted by chrysler kid View Post
+1 for a weak fan clutch or fan shroud housing damage
Do you guys even reead the posts? WTH why post up useless crap?
RockinWs6 is offline   Reply With Quote
Old 04-07-2017, 11:30 AM   #10
TECH Apprentice
Thread Starter
iTrader: (1)
 
Join Date: Mar 2015
Location: College Station, TX
Posts: 347
Default

I rechecked the pressure and it's in the operating range but on the low end. I'm going to grab a can of R134 and get it up to the middle of the operating range and see what happens.
coryforsenate is offline   Reply With Quote
Old 04-07-2017, 03:26 PM   #11
TECH Fanatic
 
Join Date: Mar 2013
Posts: 1,984
Default

What I would do is see what the pressure on the low side is when its not working. I'll bet its just low enough to cut off the compressor.
RockinWs6 is offline   Reply With Quote
Old 04-10-2017, 07:10 PM   #12
TECH Apprentice
Thread Starter
iTrader: (1)
 
Join Date: Mar 2015
Location: College Station, TX
Posts: 347
Default

Thank you for all the replies, everybody.

Turns out it looks like my pressure gauge needs replacing, maybe. I added a can of R134a and it's working fine now. It's on the upper half of the operating range now, per my gauge, as opposed to previously being on the lower end of the operating range.
coryforsenate is offline   Reply With Quote
Old 04-11-2017, 07:18 PM   #13
TECH Fanatic
 
Join Date: Mar 2013
Posts: 1,984
Default

Hey thanks for taking MY HELP...............
RockinWs6 is offline   Reply With Quote
Old 04-11-2017, 07:21 PM   #14
TECH Apprentice
 
Join Date: Oct 2016
Location: PDX
Posts: 377
Default

Harbor Freight gauge set. I have a couple rigs where close isn't close enough, had to have both high and low side and the ability to bleed back as well as fill..

Its good enough of ra once a year ac adventure..
pdxmotorhead is offline   Reply With Quote
Old 04-12-2017, 11:06 AM   #15
TECH Apprentice
Thread Starter
iTrader: (1)
 
Join Date: Mar 2015
Location: College Station, TX
Posts: 347
Default

Quote:
Originally Posted by RockinWs6 View Post
Hey thanks for taking MY HELP...............
You win the Internets, RockinWs6!

But it's great the A/C works right. Texas starts getting warm in March, so it was something that needed to get taken care of soon. And I'll visit Harbor Freight and check out a new gauge.
coryforsenate is offline   Reply With Quote
Old 04-21-2017, 05:12 PM   #16
TECH Fanatic
 
Join Date: Mar 2013
Posts: 1,984
Default

Everyone else blew you off....... TY


I know I'm great.
RockinWs6 is offline   Reply With Quote
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Engine has Hard start and sputters and bogs when you mash on the gas 1976CamaroGuy Conversions & Hybrids 2 02-06-2017 09:14 AM
Problems with my LT1 Thecatfishz28 LT1-LT4 Modifications 21 10-27-2015 12:11 PM
AC blowing but not cold bth2278 General Maintenance & Repairs 3 05-30-2015 11:16 AM
Just recharched A/C, now codes 67 and 69 AdsoYo LT1-LT4 Modifications 2 07-03-2011 07:07 PM
Vintage Air and LS1 PCM jannes_z-28 Conversions & Hybrids 7 10-14-2006 10:23 AM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not 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 Off
Pingbacks are Off
Refbacks are Off



All times are GMT -5. The time now is 07:55 AM.


 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: