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Bring on the Metal!!
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Discussion Starter #1
Where would I want to start looking to determine why the heat in my truck isn't working. It was a few weeks ago but now just blows cool yet the motor runs it's normal 200 degree temp. If I have the temp setting on full heat and turn it back to full cold I can hear the door slap shut to the heater core so I'm guessing it's not that. Any input?? Thanks.
 

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Stuck in Lidsville
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My first step would be to back flush the system, some of the coolant passages are pretty small and there may be a chunk of crud blocking the heater core.......
 

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There was just a post about this Dan in the last month with several pages of ideas but I think it ended up being the guys heater core was clogged. Check to see if both lines going to the core are hot to help determine if there is a blockage or not.
 

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Grizzly
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first i would get it up to normal temp ...feel both heater core hoses and see if they are both hot ...if one isnt flush system ...if both are blend door acuator
 

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Yes, more than likely your heater core is clogged. Had the same happen to me 00 chevy. Have to back flushed or you can do it the real lazy way like I did, Take your 2 heater hoses where they connect to the heater core and swap the lines. They are on the passenger side of the firewall. It back flushes it for you. Worked for me..
 

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I would go there next also. There is a nylon gear in there that gets stripped or worn out and I think the newer motors have a metal gear in them or at least an improved version.
 

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flush the system and put in GREEN antifreeze, not that dex-cool shit. thats why its plugged
 

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Unoffical YB Fundraiser
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There was just a post about this Dan in the last month with several pages of ideas but I think it ended up being the guys heater core was clogged. Check to see if both lines going to the core are hot to help determine if there is a blockage or not.

http://www.yellowbullet.com/forum/showthread.php?t=310315

Funny thing is my shit fixed itself. Had no heat but good temp in the motor for 2 days. Went to flush the system and the bitch suddenly got heat. Definitely will be flushing the system on the next day above 50.
 

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Bring on the Metal!!
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Discussion Starter #14
I can hear something slap shut when I turn the setting dial from full heat to full cold so I'm assuming it's the door that controls the blend of hot/cool air. I like the idea of switching the heater hoses but I'll just back flush it anyways since it's probably due for a coolant change again anyways. I haven't looked yet but are the hoses marked for coolant flow, meaning which is in and out?
 

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I kill parts
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dexcool - aka the muddy build-up in your cooling system. GM actually had a recall on the early dex-cool because it turned to sludge pretty quickly. The newer formula is better, but still turns to sludge if left in too long.

I run regular green in all my stuff, never had any trouble with the alum radiators.
 

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I can hear something slap shut when I turn the setting dial from full heat to full cold so I'm assuming it's the door that controls the blend of hot/cool air. I like the idea of switching the heater hoses but I'll just back flush it anyways since it's probably due for a coolant change again anyways. I haven't looked yet but are the hoses marked for coolant flow, meaning which is in and out?
This happened to me last winter on my 2000 silverado. I just pulled the hoses, wrapped a rag around the heater core inlet and blew air through the outlet, just a few psi. It worked great for months, I decided to fully flush and change the system when I was bored one day last summer.

I just back flushed the heater core with a garden hose and then did a full system flush. Prestone has a green antifreeze that they say can be used with either green or dexcool, I figured that would be safe.

Just feel the hoses, the hot one is the inlet.

Brent
 

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"Most" of the time its an air temp actuator. Located on the lower right side of the blower case. I personally have not had any issues with cores clogging etc.. its always been a actuator
 

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Dan, disconnect the battery and dump the memory to the hvac module by rubbing the positive cable and the negative to each other. Then hook the cables back up to the battery.If it is the temp door in the dash it will recalibrate all the doors and probly fix the problem for a short time. I have been fixin gm trucks all day for this same thing by replacing the actuators. It drops below freezing here in FL and everyone has to have heat all the sudden! Go figure!
 
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