Mechanics

CHEVY TRUCK HAS POOR HEAT, AND NONE AT IDLE.

2000 Chevrolet Silverado

Heater problem
2000 Chevy Silverado V8 Four Wheel Drive Automatic 138, 00 miles

I bought the truck this past spring and with the days getting colder noticed that my heat does not work as it should. Coolant level is fine, the hoses get hot. The truck has very little heat when idling but gives off more as you are driving around. Even full blast while driving around, it never gets warm enough to the point where I would want to take my coat off. I doubt it would even melt away ice. I saw someone else on this site have a similar problem and they said they " flushed" out their heater core and it seemed to work fine after that. Is that a feasible solution or is there something else going on here?
Avatar
47bobber
October 14, 2008.




Replace the thermostat and see what happens

Tiny
Rasmataz
Oct 14, 2008.
We need to first see how HOT your truck is actually getting. What does the guage say? It should run about 210 degrees. If it is, feel of BOTH hoses going into the heater core, through the firewall. Is ONE hot and the other cool? OR coolER? If so, the water may not be circulating through the core. Keep in mind that if the water is circulating, and the blower is on, blowing air through the core, the water temp on the outlet side of the heater core will be slightly cooler. If the water is NOT circulating through it, one will be considerably cooler. If this is the case, I only recommend replacing it. If it appears to be circulating, I would start checking the operation of the blend door in the evaporator case. If it's mostly closed off to the core, little or no air will pass through the heater core, thus no hot air will reach your cold face or feet. Try that. If the truck is, in fact, not reaching 210 degrees, replace the thermostat.

Tiny
Jasonray
Oct 16, 2008.
Truck is reaching the correct running temp of about 210 degrees and does not over heat. A bad thermostat is unlikely. The water does seem to be circulating because both hoses are getting hot. The outlet hose is slightly cooler. Where would I find the blend door, and how would I go about replacing/fixing it. What would stick out as obviously wrong with it? Thank you

Tiny
47bobber
Oct 18, 2008.
In my experience if the heater core is plugged, you'll you'll get heat for a short time and then the air will blow cold. This is because there is flow in and out but very little out. So the core fills up with coolant and when you turn on the heat it initially blows hot but the coolant is stagnant because of the output. So if you turn the blower off for a bit and back on you'll get heat for another few minutes. Is this happening to you? Also, if the thermostat is stuck opened then coolant won't reach operating temp. Or will take a very long time to reach. It depends on the cooling system. If you have good flow and a heavy duty radiator (three rows inside) then the coolant will never get hot. Also i've flushed several cores over the years mostly using the water hose. If it's easy enough to remove both heater hoses, why don't you block the hoses and check the core for flow using either air or the garden hose. You'll know immediately and you won't lose much coolant. If you use water be sure you don't put full steady pressure. Short bursts. If it's clogged and dirty be sure you flush the complete system with the prestone flush kit. Flush it, don't just drain it. Let us know how you did

Tiny
Autofixer2
Oct 18, 2008.
The blend door is in the EVAP case. Don't try this if you're scared. The dash is gonna have to come out. That's a process all by itself. The AC system will have to be discharged as well. Remove the case from the firewall. Before we jump into that, lets check the operation of the actuator first. The door in question is controlled by an electric actuator that recieves it's signal from the AC control head. I don't have the information in front of me because its sunday and I'm at home but I think it's on top of the evaporator case and nearly impossible to get to. I'll know for sure tomorrow when I get to work and can look at my computer there. This is WAY more likely than the actual door being stuck, although that can happen. Rats can build nests in there and block the door. The blower can suck a Sonic napkin out of the floor into the case and there's no telling where it'll end up. But, before you go to that trouble, check the actuator. Try turning the temp control from hot to cold. (With the vehicle on) Do you hear ANY change at all? Listen closely behind the glove box for ANYTHING. Start there.

Tiny
Jasonray
Oct 19, 2008.
The other day I flushed out the heater core with a garden hose. Used short bursts of water pressure. The heat seems to be working much better since I have done this. Cross my fingers, hope it stays that way.

Tiny
47bobber
Oct 22, 2008.
Just a footnote: if the heater core was in fact plugged, then the coolant system may very well be in dire need of flushing. Otherwise the problem may reoccur. Good luck
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Tiny
Autofixer2
Oct 22, 2008.
Sounds like my issue. Found out the problem was the "Air Door Actuator", GM P/N 52474810. This part is about $100 at the dealer. Save some money and get it at O'Reilley's Auto Parts for $46 with a LIFETIME WARRANTY!! Also you can check ebay and find them there.

The actuator is underneath, near the center of the underside of your dash accessed from the passenger side. You'll need to remove the three screws that hold that cover on and you'll see it there.


http://www.2carpros.com/forum/automotive_pictures/332933_20090316_01524_1.jpg



Here is the post that turns the flap inside. You can manually move it if you are in a pinch where it's REAL cold and you need heat till the new part goes in.


http://www.2carpros.com/forum/automotive_pictures/332933_20090316_01526_1_1.jpg



http://www.2carpros.com/forum/automotive_pictures/332933_20090316_01526_1.jpg



Another picture here shows part of the problem. I believe the problem is that little blue gear which is attached to some type of potentiometer that has contacts exposed which gets grease in there. Also note another indication it was going to fail: Check the motor where it has markings on it. It says: "CHINA" Bet the whole unit was made there. ::sigh::


http://www.2carpros.com/forum/automotive_pictures/332933_20090316_01523_2_1.jpg




http://www.2carpros.com/forum/automotive_pictures/332933_20090316_01523_1.jpg



Here is the new one installed. This one I bought from O'Reilley, using the GM part number 52474810 THIS PART ALSO HAS A LIFETIME WARRANTY!!!! :)


http://www.2carpros.com/forum/automotive_pictures/332933_20090317_01530_1.jpg


Tiny
Alwcurlz
Mar 17, 2009.
Just wanted to tell you that the pictures are great! They helped me fix my actuator problem in short order. Thanks again.

Tiny
Bdome
Oct 26, 2009.
No problem bdome! Post anything else that you may have questions or problems with!

Tiny
Alwcurlz
Oct 26, 2009.

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