Heater takes forever to kick in..

[gofish]

Just bought a 99 Tahoe 5.7 4wd. LOVE the truck. My only complaint so far is the heater takes about 20 minutes to kick in. For example, this morning I went out started the truck, made sure the heater was on, and waited about ten minutes. Went back out and still blowing cold air. About ten minutes down the road it finally starting blowing warm air. Is this normal? The motor temp was fine, coolant level is ok. Any suggestions?
Thanks

 

[TahoeGoBoom]

is the engine temp staying cool as well, or does the engine heat up?

 

[96fleetwood]

Heater core may need to be flushed.

 

[treepete]

to me this sorta sounds like you need to replace the thermostat.

 

[gofish]

I know the thermostat was replaced about 1.5 years ago (along w/ the radiator itself). The guy gave me the service records. Not that it couldn't have gone bad again. The engine temp goes up to normal levels pretty quickly though.
Maybe the heater core is the culprit. Just wanted to see if anyone else had a similar issue. Once it finally heats up it works just fine.

 

[TahoeGoBoom]

yea, i would check the heater core.

 

[bsamoul]

Heater cores are such a PITA

 

[peterey2]

flushing them out is very easy. replacing is def a pain.

 

[swanie2000]

I had the same problem with my 95 Tahoe I just bought. Engine was at normal temp, but heat was cold. It turned out to be the little vacuum operated valve on the heater lines, in the engine bay. Double check that this valve is working.

Swanie

 

[gofish]

I had the same problem with my 95 Tahoe I just bought. Engine was at normal temp, but heat was cold. It turned out to be the little vacuum operated valve on the heater lines, in the engine bay. Double check that this valve is working.

Swanie

Thanks, I'll check that out too. Been super busy and haven't had the opportunity to pop the hood. I'll post my findings when I get a chance.

 

[sick_46]

how did you check to be sure that valve is working? Also pics of the valve?

 

[swanie2000]

It is a vacuum operated valve, mounted 5" from the firewall, in the engine compartment, hanging on the heater hoses that go from the engine, to the heater core, on the passenger side.

You can push the valve closed by finger and thumb pressure. Be sure you can push it closed by hand. Then take a piece of vacuum line, and suck on one side, and see if you can operate the valve with vacuum.

If all that works, then check that you have vacuum. The vacuum is switched by an electric vacuum solenoid, mounted on the receiver/dryer of the air conditioner, which is located about 1 foot up from the valve, mounted on the firewall, on the passenger side.

From the best I can tell, the solenoid is turned on/off with the center knob on the dash, the one with the heat/cool blend icons. Turn all the way over to the cold side, turn the AC button on, and the solenoid should activate, and pass vacuum on to the valve. This action, turns off the hot water going into the cabs heater core, and helps the air conditioner work better.

I suspect, your valve is stuck closed, or the solenoid is stuck on. Also, it was weird, but it DID matter what side of the solenoid had the engine vacuum. I noticed, if it was back-wards, the valve would stay closed, even after the solenoid was commanded to be off. I can't remember wich side is what, but just wanted you to try swapping the vacuum hoses on the solenoid if it is not operating correctly.

Hope this helps...

Swanie