Heater goes "tick,tick,tick,tick,tick"

[CrazyDave]

I believe the problem is the air actuator control. I have a 93 GMC ecsb 5.7. As far as I can tell from the manual there are 3 actuators. How do I know which one is bad? Do I have to remove the entire dash to access it?

 

[RHamill]

Tell us more of your diagnosis. There could be anything from something floating around in the blower fan, to a blend door actuator sticking.

What mode does it do it in?

Hot or cold?

A/C on or not?

Which speed on fan?

 

[CrazyDave]

OK, when I turn the ignition key to start the engine it starts ticking for about 30 to 45 seconds and then it stops. It does it on heat and AC. Fan speed doesn't matter. It will tick with or without the fan on, as well as with or without any mode selected. It does it when all modes are turned off. It stays quiet until I turn the key and stop the engine, then it ticks for about 30 to 45 seconds and stops.

So long story short.....it ticks at start up then stops. Then it ticks when i kill the engine then it stops. I also noticed that it doesn't direct the air to the floor when I select it. But I do have air out of the front vents and on the windshield.

 

[Devs93]

You need a blend door actuater about 30/40 bucks and kind of a pita to change

 

[Blakestuhh]

Mine makes a ticking sound when I go from hot to cold and it will still be making the noise after it has got to either side!

 

[Devs93]

its the blend door

 

[Blakestuhh]

PITA to change huh? What is all involved?

 

[CrazyDave]

You need a blend door actuater about 30/40 bucks and kind of a pita to change

Thanks man. Do you think I can get to it by removing the glove box? Or do I need to remove the passenger side of the dash?

 

[1993GMCSierra]

It's the Recirculator door, not the blend door. No point buying parts you don't need.

My old GMC did it, my new one does not. If the blend door was bad, you would only have full heat, or full A/C. You would not be able to adjust the temperature.


Wait for the ticking to stop, then press the "REC." button on the heater panel. Usually it'll start ticking again.

The easy "fix" is the unplug the connector for the door, this way it'll stop. Downside is you will not be able to switch from outdoor to indoor (recirculated) air for maximum A/C efficiency. Then again, as it sits, it's not working anyways.

I don't know what all is needed to do this, I just lived with it, one of the many quirks that old truck had.

 

[CrazyDave]

Thanks for the help. It does start ticking again when I push the recirculate button. It sounds like I may have more than one problem here. I think both of you guys are right. Because the air wont blow down on the floor. Does the blend actuator control where the air is directed? Such as on the windshield, through the dash vents, and on the floor? If its any help my truck is equipped with the digital thermostat in the dash. I'll have to see if I can find some drawings of the heater unit. Maybe in the LMC catalog.