Heater Question

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Jan 27, 2010 | 01:44 PM

Erikh425

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From: Northern MN

Heater Question

I have noticed that my truck doesn't get as warm as I would like when it is below zero. I attributed this to the fact that there is alot of space to heat. This morning I cranked the rear heat and the front heat and noticed that the heat coming from the rear is alot warmer than the heat from the front. I have done a couple searches in the heat/AC section and I am pretty sure that it comes down to a few things.
-Blend door actuator
-Resistor on the unit in the engine bay
-Thermostat

Seeing as the air in the rear is nice and warm I think I can rule out thermostat. I would like to hear other opinions, and what I should check next, actuator or resistor.

Thanks,
EH

Jan 27, 2010 | 02:12 PM

tdappleman

Fleet Mechanic

Joined: Sep 2002

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From: Greensboro, NC

The Excursion has a vacuum operated valve which can close off the water flow to the heater core. You'll see it on the passenger side inline with the heater hose. Make sure you don't have a vacuum leak or a valve which might be closed or partially closed.

Jan 27, 2010 | 02:28 PM

Erikh425

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Posts: 79

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From: Northern MN

Any chance you have a picture of this? I am hoping that I can pull back the carpet and it will all make sense. I have a Haynes manual at home. I will take a look when I get there.

Jan 27, 2010 | 04:02 PM

tdappleman

Fleet Mechanic

Joined: Sep 2002

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From: Greensboro, NC

Hope this helps - if you suspect it you could always get an inline connector (unsure of hose size) and do a test. It really isn't going to come into play until summer and you need A/C again. This door shuts the water flow to the heater core when the A/C is on to boost the performance.

and a closer shot:

Jan 27, 2010 | 05:16 PM

Erikh425

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From: Northern MN

Is there actually also a blend door actuator type thing under the passenger side dash behind the glove compartment too?

Jan 28, 2010 | 09:23 AM

Erikh425

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From: Northern MN

I took the truck for a drive today, and maybe the lack of warm air is in my imagination. After the truck is at normal operating temp I stuck a thermometer in the front vent and the rear vent. Both read right around 95deg at idle and jump to about 106deg when I am running down the road. These numbers seem warm enough, but I am not sure what they are supposed to run. It was -15degrees this morning. Anybody know if this is a normal temp, or should I dig into something?

EH

Jan 28, 2010 | 10:06 AM

tdappleman

Fleet Mechanic

Joined: Sep 2002

Posts: 1,388

Likes: 2

From: Greensboro, NC

There is a blend door under the dash - but it sounds like you're getting warm air to me. I've never put a thermometer in the vents but you're probably pretty close. You can check the blend once your truck warms up by changing the temp setting - not sure if you have auto climate control or manual but you can check either way.