2003 Chevy Silverado Has No Heat- Just Blows Warm

logandean234
Posts: 1
Joined: Thu Nov 08, 2012 3:37 pm

2003 Chevy Silverado Has No Heat- Just Blows Warm

Unread post by logandean234 » Thu Nov 08, 2012 3:42 pm

I have a 2003 Chevy Silverado 1500 V8 single cab. My heat doesn't work. I know practically nothing about it either. The A/C works on all speeds and the blower works great. The air just does't get hot or even mildly warm. Going into winter, I need help ASAP.

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ProTech
Posts: 652
Joined: Wed Oct 17, 2012 10:08 am

Re: 2003 Chevy Silverado Has No Heat- Just Blows Warm

Unread post by ProTech » Thu Nov 08, 2012 8:31 pm

This is usually one of two things that causes a lack of heat coming from the vents. First, and easiest to check is a clogged heater core. If you have a restriction through the heater core, it will not produce enough heat for inside the vehicle to warm up. You can check this by getting the truck up to operating temperature and then touching the heater hoses that are coming from the right side of the firewall in the engine compartment. One is an inlet and the other is an outlet. They both should be just about too hot to grab if the heater core is working properly. If one is hot and the other is just lukewarm or less, then you do have a restriction. A quick way to fix this is to do a backflush on the heater core itself. You can do this by removing the heater hoses and then using a garden hose with the water turned on to flush both directions and get any debris out of it. Usually you will see a large blast of very dirty coolant and debris right when you start to flush it. Compressed air helps too, but be careful not to use too much pressure into the core or it can rupture. Reinstall the hoses, fill with coolant and you're back in business with some great heat!

Now, secondly, this could be an actuator problem inside the heater case inside the truck, under the right hand dash area. There is a temperature actuator that moves a door inside the case to direct either cold air or hot air depending on what you select on the control head. If there is a problem with this actuator, it can become inoperative in one direction.
To check this, you would actually need a proper scanner to be able to 'watch' what the actuator is doing when it is commanded a certain direction. If the actuator needs changed, it isn't too bad of a job either. You would have to removed the lower heater case cover, below the right side and center of the dash area. The actuator is located right on the bottom of the case, just about in the middle. Once replaced, you have to do a calibration process which is best done with a scanner, but if you don't have one pull the HVAC fuse for a couple minutes and it will calibrate automatically after that.

Good Luck!
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Chevy Silverado Temperature Actuator Blows Cold Air
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