heater control problems

regcab02HD · February 8, 2002

This morning when I left for school in my HD, I put the heater on full heat, setting number 3. After about 3 minutes it started feeling good so I turned the heat to about medium. And left the setting on 3. It still seemed to be getting hotter so I turned the setting to 1 and turned the heat all the way down to cool. But nothing changed, it still was getting hot. I arrived to school after about 7 minutes and played with the controls alittle more, but nothing happened.

So I turned my pickup off and then started it again. The controls worked fine. What could've happened? Could I have been turning controls too fast? Anyone had this problem before?

antig24 · February 8, 2002

Hmmmmmmmm, I've never heard anything like that on the HD's before ???

doverarjim · February 8, 2002

Mine is not a HD but my heater seems to work the same. You get the cab warm and start to turn the blower motor down and then it seems to get warmer and warmer so I turn the heater control to about 1/2 and then turn the blower to 1 and then it takes a minute or two and it seems to get cooler and then I can adjust it from bottom up. It may have something to do with motor temp. I have not paid much attention to the temp gauge when it is happening but I know on my 86 it was very much in line with motor temp.

CMNTMXR81 · February 11, 2002

Today's engines run hot on purpose for emissions reasons. Most run about 210 degrees, which means you have 210 degree coolant flowing through the system which eventually makes it's way through the heater core which is then blown into the cabin.

Mine gets hot enough sometimes where I have to crack a window.

MemphisDoug · February 11, 2002

I've noticed that with my truck, I have to keep the heater control and fan control both way down in order to have the truck at a comfortable temperature. Otherwise, it smokes me out of there with way too much heat

DBM · February 12, 2002

Mine did something similiar, but the opposite. I've only had my HD for about 2 weeks. I could adjust the fan speeds, but I couldn't change the temp or the vent selection. It was a very cold drive to work that morning with the defroster blowing sub-freezing air. After work that day it was back to normal.

My only guess, is that there is a circuit breaker that controls the climate contol that trips on startup.

Anyone else have similiar probs/answers?

CMNTMXR81 · February 12, 2002

Sounds like an improperly functioning thermostat to me. The only circuit breaker/fuse on the HVAC system is for the electric motor on the blower, back lighting the controls and the A/C compressor.

silverado man · February 12, 2002

this same thing happened to me this morning. I started the truck with remote start but when i got out there it wasnt wam like it usually is. I thought didnt turn the fan on high but i was set. I drove to work still no heat, but i did notice that the rescirc. and the fresh air button lights were on, also had it on full heat still no heat after getting to work, and the vent selector either. Dont know what was going on, got to work shut the truck off and turned it back on and work fine. ??? ???

CMNTMXR81 · February 12, 2002

It could be anythiing really but just sounds like a sticky t-stat to me.

tsbrewers · March 14, 2002

this same thing happened to me this morning. I started the truck with remote start but when i got out there it wasnt wam like it usually is. I thought didnt turn the fan on high but i was set. I drove to work still no heat, but i did notice that the rescirc. and the fresh air button lights were on, also had it on full heat still no heat after getting to work, and the vent selector either. Dont know what was going on, got to work shut the truck off and turned it back on and work fine. ??? ???

I had the exact same problem, remote start too. Now I don't have any fan speeds except for high??

Brew

Bowhunters · December 6, 2006

My 2001 Sierra Ext Cab is doing the same thing.

It started out that the temp's were only sticking when selected to full hot but now a year later it sticks at about 3/4 hot.

If I shut off the truck for a couple minutes and then restart it I get control of the heat back, as long as I never exceed about the 3/4 temp position on the temp rheostat I can turn the temps down with no problems.

Makes me wonder if the foot heat valve that mixes hot air and cold air is sticking when the valve gets hot, maybe the valve needs some lubricant?

jedcooper · December 7, 2006

Mine did that right before I bought it.

The used truck dealer said his mechanic was going through a checklist.

He put the truck on heater, let it warm up the cab for a while, then switched to

A/C and let it cool for a while. He then switched back to heat and it would not.

Can't remember the term, but some switch behind the heater/ AC controls was out and they took it to the dealer. Sounded like an easy fix, not sure of the cost.