2000 Silverado Heater not Working

[aenglema]

Hello All,

I have a 2000 Silverado LS with a 5.3 liter engine. My heater only blows out luke warm air and my AC cycles on and off, even with the switch in the off position. I realize I may have multiple problems here so here is some info.

 

When I have the engine warmed up, the heater only gets to luke warm. All locations work. Defrost, vent, foot. I do not have dual zone climate control. With the dial in cold it feels like the AC is on.

 

For the heating:

I removed the actuator for the heater blend door and the heater blend door does move freely. I applied 9VDC to terminals 5 and 6,7 and the actuator did move back to the center position. I have attempted the many different ways to re calibrate the actuator. No change. I do have 2 fuse boxes. One in the engine bay and one inside the dash by the drivers door. I pulled both fuses during this test. Both heater hoses are hot, or at least really warm, with an engine temp of about 200.

 

For the AC:

Pretty sure the AC compressor cycles on and off even with the switch in off. Can't think of anything else in the engine compartment that would do that. With the cab fan on, it does feel like the AC is on all the time, even with the AC switch light off. Can't feel a difference when I press the AC switch. I can't get into a position to see the AC clutch to see the status of it. I think if I remove the intake air flow tube I might be able to see it. There is a hum, or a whine, coming from inside the engine compartment. I can't tell where it is coming from as my radar is getting bad these days.

 

Besides any help offered, which I definitely appreciate, I have a couple operational questions. Where does the cold AC air come into the cab in relation to the heater box. Just trying to figure out air flow. With the truck running, would it do me any good to take off the heater blend door actuator and manually operate the door? Will that tell me the heater is good and my problem is the AC is on all the time? I figure cold plus hot equals warm.

 

Thank you.

[NBSFan]

My truck is the latter 99 Silverado 1500 and it has 3 actuators. I believe your truck has 3 different actuators as well

.

1 in the top of your dash

1 under the dash above the left side of the tranny hump

1 under the glove box near the fan blower

 

Which location did you remove your actuator from ???

[aenglema]

The one by the transmission hump. Can't imagine getting to those others. If I was to guess, I would say one of the others is for fresh air and the other to direct air to the different ports. I think both of those are working OK.

[aenglema]

Kind of weird experience a little while ago. I disconnected the plug at the AC compressor to prevent the AC from influencing the heater troubleshooting. Temp on the truck went to normal. Heat blowing out of the vent with the recirc button activated and the air was almost warm. I switched it to feet and the selection automatically went to fresh. Colder air now on my feet. When I put it back to vent, it went to recirc and the air was colder and would not heat back up. I tested while driving and while stopped. Outside temp is 33.

 

Also I am not getting any clicking from anywhere in the dash.

[aenglema]

Thanks for the help... not!!!!!!!!

[muddkatt]

Thanks for the help... not!!!!!!!!

 

Glad we could assist you.

[txab]

AC may run at any time. Have you flushed the heater core? Is your cooling system completely topped off with no air pockets? These items can cause poor heater performance

[rjgti]

due to your NOT response all i will tell you is change your fawking air filters

[BLACK DEATH]

I have the same exact issues.....

 

You can tell it's the heater core by feeling the two hoses and if one is a lot cooler than the other, core is clogged. I do this test when it's a cold engine as the hoses will heat up as engine temps warm up. So if one hose is cooler after this test, pull the heater hoses off the wall fittings and flush the heater core both directions with a water hose on full blast.

 

Ac cycling... if your button is on circulation, or vent, one of these on the hvac controls while it's on defrost or other certain settings it is going to cycle the compressor to remove humidity in the cab. Mine did this until I figured it out. If it still cycles, I just unplugged the pressure switch at the dryer until winter is over.

[Josh Wright]

I am having some similar problems with my heater. I have a 2000 gmc yukon, and replaced the actuator on the passenger side. Now the rear vents work great, but I am not getting any heat at all in the front. I would appreciate any help!

 

Thanks!