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2004 Silverado

rlk

Bronze Member
GOLD Site Supporter
Last Friday I had to have the battery replaced in my 2004 Silverado LX Extended Cab, with 84,000+ miles. Prior to the battery problem, there have been no problems with the vehicle.

On the way home from the shop, the AC was not working correctly. The AC has electronic controls with the driver and passenger being able to set different temperatures. The passenger side worked as it should, i.e., plenty of cold air. The vents on the drivers side would only blow extremely hot air, like the heat was on high.

I turned the AC off for a few miles and tried it again with the same results. This morning I tried it again and it is doing the same thing.

Since the only change that was made to the truck was replacing the battery, could that have caused the AC on the drivers side to fail?

Any suggestions on what to check before I have to take it to a repair shop?

Thanks, Bob
 

muleman

Gone But Not Forgotten
GOLD Site Supporter
Fuse block under the hood drivers side. They may have split the circuit and used separate fuses. It may be a sticking control valve for the heat. Those split comfort systems are a PITA.
 

waybomb

Well-known member
GOLD Site Supporter
If it's not a fuse, I'd turn every switch off before turning the car off, roll up all the windows, unlock all the doors. Turn it off, Disconnect the battery. Wait a half hour. Hook it all back up. Start the truck up, then try the ac.

Computers in cars are a funny thing..............
 

Snowtrac Nome

member formerly known as dds
GOLD Site Supporter
i aggree try the last post every thing will be in the same fuse ecept the ac compressor likely it's not related my experiance with those trucks up here that have more options than a caddy is after a few years all them electronics start to act up both switches and control modules give me old and simple.
 

rlk

Bronze Member
GOLD Site Supporter
Fuse block under the hood drivers side. They may have split the circuit and used separate fuses. It may be a sticking control valve for the heat. Those split comfort systems are a PITA.

Thanks Muleman. I looked at all the fuses that said anything about AC, heat or blower. In addition to those you mentioned, I found a couple more fuses in the panel inside the cab, by the driver's door. All looked good.

Where is the control valve, and how hard is it to get to it? Sure hope it is not under the dash.

Bob
 

rlk

Bronze Member
GOLD Site Supporter
If it's not a fuse, I'd turn every switch off before turning the car off, roll up all the windows, unlock all the doors. Turn it off, Disconnect the battery. Wait a half hour. Hook it all back up. Start the truck up, then try the ac.

Computers in cars are a funny thing..............

Thanks Waybomb. I'll give that a try as soon as it cools off a little.

Bob
 

muleman

Gone But Not Forgotten
GOLD Site Supporter
The control valve on my 98 suburban was on the passenger side almost at the firewall. Chinese plastic POS when I replaced it. The 05 has not been a problem but the a/c quit 2 years ago.
 

rlk

Bronze Member
GOLD Site Supporter
If it's not a fuse, I'd turn every switch off before turning the car off, roll up all the windows, unlock all the doors. Turn it off, Disconnect the battery. Wait a half hour. Hook it all back up. Start the truck up, then try the ac.

Computers in cars are a funny thing..............

Tried this suggestion Waybomb. AC vents on the drivers side still blowing very hot air while the passenger vents are blowing cold air. Stupidest thing I ever saw.

Guess I'll be looking for an AC shop next week.

Thanks for the suggestions.

Bob
 

muleman

Gone But Not Forgotten
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Tap on the drivers side thermostat. It might be stuck in the heat position.
 

rlk

Bronze Member
GOLD Site Supporter
When I first started the truck this morning, the AC was still blowing very hot air on the drivers side. I turned everything off and started home. After about 50 miled I switched the AC on and had cold air. Somewhere along the way something reset itself and all appears to be ok now. No telling how long it will last though.

Thanks for all the suggestions.

Bob
 

rlk

Bronze Member
GOLD Site Supporter
Well, my problem returned yesterday afternoon. About halfway home the a/c vents on the drivers side started blowing extremely hot air. Guess I'll be looking for an a/c shop after all. With our temps currently running in the 100 degree range I may have a little wait before a shop can get to it.

Bob
 

Dargo

Like a bad penny...
GOLD Site Supporter
Somewhere in the system that controls the dual climate zone you have a loose or corroded ground. In roughly 40 years of working on vehicles, I've seen more problems with ground wires that looked fine until I removed them. Then I saw a lot of corrosion that prevented a good connection. The ground problem is probably 2nd in the "mystery" column to the spak plug wires in an Olds 98 causing the transmission to chatter, not shift and basically try to self destruct itself. I never believed that fix until I did it myself on an Olds 98 I had that started having transmission problems. In the dark with the hood open and no lights on, I could see hundreds of little arcs on the plug wires. Weird.

Anyway, the good news is that it sounds to me like the fix will cost you nothing. The bad news is it's probably going to be a bitch to track down. It's most likely under the dash. I'd start by trying to see if you can wiggle any wire at it's connection point. Even if all seem tight, you may be surprised and have fixed the problem. Good luck.
 

FrancSevin

Proudly Deplorable
GOLD Site Supporter
AC vents are controlled by vacuum. It sounds like you might have a vacuum problem. One of the doors that controls the air flow may be sticking or, you may have a loose vacuum hose.

WD-40 might fix the former, duct tape or electrical tape might fix the latter.

Finding and accessing the fault may be problematic.

Today's cars and trucks are designed to be assembled, not repaired.
 

waybomb

Well-known member
GOLD Site Supporter
I think that even if the vacuum motors were 100% out of whack, he should still not be getting hot air.

It sounds to me as if there's a couple of problems, probably something with the mix door and something with the heater control valve. Hot water should not be circulating through the heater core when controls are set to a/c and cold.
 

FrancSevin

Proudly Deplorable
GOLD Site Supporter
I think that even if the vacuum motors were 100% out of whack, he should still not be getting hot air.

It sounds to me as if there's a couple of problems, probably something with the mix door and something with the heater control valve. Hot water should not be circulating through the heater core when controls are set to a/c and cold.

True, unless he has passenger/Driver controls.
And the heater core will likely have some flow of water and always be warming the air in the summertime because,,,,, it is hot outside.

heater/cooling control module on my 86 benz did this very thing.
 

rlk

Bronze Member
GOLD Site Supporter
Picked up the truck Monday. Seems there are 3 actuators under the dash. One for the drivers side, one for the passengers side, and one that controls recirculating air. I had 2 bad actuators, the one on the drivers side and the one that controls the recirculation of cabin air.

The actuators were roughly $230 each.

I told the mechanic to forget about replacing the one that controls recirculation, as that one was the hardest to get to, and would have had the highest labor charge as the center console has to be removed in order to get to it. I just didn't think it was worth replacing when all it controls is recirculation of cabin air.

So he replaced the actuator on the drivers side, charged me $421 and sent me on my way.

He did tell me that he thinks GM has a bad design on the actuators because the actuator assembly includes the electronics, the motor, and the valves that mix the hot and cold. Other manufacturers have the electronics separate so when they go bad there is less to replace.

New cars with all the fancy computer controlls are nice, but sure are expensive when things break.

Personally I'd just as soon have a heating/ac that is adjusted by cables and levers; window cranks vs electric windows; manual seats vs electric; etc. Kinda hard to find trucks like this any more.

Bob
 

Doc

Bottoms Up
Staff member
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Strange that they went out when the battery was replaced. Especially two at once.

I have an 05 Silverado crew cab with the dual heat /ac controls. Guess I know what's coming around the bend. I agree, I would much prefer the heat and ac being adjusted by cables, but I do like electric winders .... it's a long ways to reach the passenger side or back seats if I want to put one of those up or down.
 

muleman

Gone But Not Forgotten
GOLD Site Supporter
I would give up the a/c to have a simple slide control for temp and manual vents that you pulled a lever to open. It does not have to be this complicated. Same with 4wd. Auto everything costs big bucks and has a shitload more trouble.
 

rlk

Bronze Member
GOLD Site Supporter
Strange that they went out when the battery was replaced. Especially two at once.

That's a mystery to me as well. Guess I'll never know what happened to cause them to fail.

Bob
 

JimVT

Bronze Member
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This trouble is good for me as I plan on picking up a 4x chev 3/4 in the 10 to $16,000 range ton next month. It should be close to that year . My 85 c20 is getting brittle. Most of the plastic is just crumbling from age. I went to work on a headlight last month and that plastic tab holding fell off. At 300,000 miles and working good makes me want a diesel again. i hope the next one will go 27 years then I'll be 88 and time to stop driving.
thanks
Jim
 
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