98 Dual climate control issues/ NEED HELP
Thread Starter
Burning Brakes
Joined: Jan 2004
Posts: 953
Likes: 4
From: Guelph Ontario
98 Dual climate control issues/ NEED HELP
Started my 98 yesterday only to notice that the temperature control reading was stuck at 75/76F. Could not adjust temperature up or down just stuck on 75/76. Driver side vents were blowing warm air and passenger side was blowing cool air with more force compared to drivers side. Eventually I was able to turn down the temperature whichnow sticks on 61/60 which took about 20 minutes, but no luck in turning temp back up to 70-75-80. It just stuck at 60/61. Then the temperature was cold on drivers side too but still not blowing cool air like the passenger side. Checked the DTC and no codes on HVAC. Left the car sitting for 4-5 hours and same issues as before. Removed the #8 and 27 fuses and still no change. Need you help. 
"My Dad's a TV Repairman"
Joined: Jul 2014
Posts: 471
Likes: 153
From: San Diego
In the absence of HVAC codes, I would try the easiest possible fix, and that would be the old low-freon solution. When the dual-climate system senses low refridgerant, it will typically only blow cold on one side. Try a bottle of freon/lubricant with the gauge on it (around $30 at P Boys or Vatozone), and see how much she takes. Solved my dual zone,only-oe-zone-cool issues.
Team Owner
Joined: Jul 2006
Posts: 22,150
Likes: 4,165
From: Kannapolis NC
If it was happening to my car, I'd go into the diagnostic code display, write down what I had. Then, clear them all and try again and see if the a/c works, or what codes come back. You may just have a bad HVAC control unit. If so, it's not a disaster, I bought one used for under $150 from VetteNuts.net that works great.
Thread Starter
Burning Brakes
Joined: Jan 2004
Posts: 953
Likes: 4
From: Guelph Ontario
Thread Starter
Burning Brakes
Joined: Jan 2004
Posts: 953
Likes: 4
From: Guelph Ontario
If it was happening to my car, I'd go into the diagnostic code display, write down what I had. Then, clear them all and try again and see if the a/c works, or what codes come back. You may just have a bad HVAC control unit. If so, it's not a disaster, I bought one used for under $150 from VetteNuts.net that works great.
Burning Brakes
Joined: Nov 2001
Posts: 1,162
Likes: 81
From: Bel Air MD
A few years ago I had a similar sounding problem. I could not change the temperatures and had difficulty in turning the unit off. I tried to get the unit repaired but the place I sent it could not repair it. I had to buy a remanufactured control unit.
Thread Starter
Burning Brakes
Joined: Jan 2004
Posts: 953
Likes: 4
From: Guelph Ontario
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Team Owner
Joined: Jul 2006
Posts: 22,150
Likes: 4,165
From: Kannapolis NC
I disagree. These units are very reliable except for the dim display and button lights, which can be easily fixed. The function is very solid. I'd go used unless I found a rebuilt one for about the same price.
Thread Starter
Burning Brakes
Joined: Jan 2004
Posts: 953
Likes: 4
From: Guelph Ontario
Le Mans Master
Joined: Mar 2011
Posts: 6,835
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From: Columbia SC
Remember a remanufactured unit will only have what is wrong fixed. That just means that was wrong may last longer but not other things. Most likely they were repaired to fix the dim display.
Thread Starter
Burning Brakes
Joined: Jan 2004
Posts: 953
Likes: 4
From: Guelph Ontario
Had the AC checked at a reputable shop this afternoon. Looks like it's the control unit. The freon was spot on. Contacted my local GM dealer, none available in Canada, called a US dealer same response, none available. Now I need a good working unit GM part # 16254311, if anyone has one that is fully functional, send me a PM with price and shipping to Buffalo 13404.
Team Owner
Joined: Jul 2006
Posts: 22,150
Likes: 4,165
From: Kannapolis NC
Had the AC checked at a reputable shop this afternoon. Looks like it's the control unit. The freon was spot on. Contacted my local GM dealer, none available in Canada, called a US dealer same response, none available. Now I need a good working unit GM part # 16254311, if anyone has one that is fully functional, send me a PM with price and shipping to Buffalo 13404.