01' Tahoe no heat help needed
November 26th, 2010, 5:43 PM
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01' Tahoe no heat help needed
Hi there,
Have done a quick search but have not found what I'm looking for.
Wife's 01' Tahoe. Dual zone heat.
Heat works in back but not in front cabin. I know they are two separate systems but thought it relevant.
Started under hood, ran vehicle to bring up temp and in/out coolant lines warmed up. In more so than out. Larger difference when cabin blower is operating.
So I assume blend door issue.
The upper blend door on the drivers side seems to be functional. If I disconnect the wire and switch settings at the control panel I get no changes in which vents are blowing. Hook it back up and defrost, floor and upper all switch properly.
There is another blend door motor on the passenger side, just above the passenger side of the tranny hump. No matter what combo I set at the control panel it does nothing. Removed it and can manually operate the door but it does not make a major difference, almost none.
I'm a little stumped here.
I have not pulled the upper blend door motor since it's in a confined space. I understand though that it actuates two cams, one for AC and the other for defrost?
Is there a length of travel for motors shaft to actuate both cams? is it possible for the motor to function and activate the defrost cam but not the AC?
ANy help would be greatly appreciated.
Best
Scott
Have done a quick search but have not found what I'm looking for.
Wife's 01' Tahoe. Dual zone heat.
Heat works in back but not in front cabin. I know they are two separate systems but thought it relevant.
Started under hood, ran vehicle to bring up temp and in/out coolant lines warmed up. In more so than out. Larger difference when cabin blower is operating.
So I assume blend door issue.
The upper blend door on the drivers side seems to be functional. If I disconnect the wire and switch settings at the control panel I get no changes in which vents are blowing. Hook it back up and defrost, floor and upper all switch properly.
There is another blend door motor on the passenger side, just above the passenger side of the tranny hump. No matter what combo I set at the control panel it does nothing. Removed it and can manually operate the door but it does not make a major difference, almost none.
I'm a little stumped here.
I have not pulled the upper blend door motor since it's in a confined space. I understand though that it actuates two cams, one for AC and the other for defrost?
Is there a length of travel for motors shaft to actuate both cams? is it possible for the motor to function and activate the defrost cam but not the AC?
ANy help would be greatly appreciated.
Best
Scott
November 26th, 2010, 9:30 PM
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Welcome to the forum.
Are the in/out hoses on the rear heater core about the same temp? I don't know if there is a valve in the heater hose lines but if there is, might check it.
Are the in/out hoses on the rear heater core about the same temp? I don't know if there is a valve in the heater hose lines but if there is, might check it.
November 27th, 2010, 9:22 PM
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I had an 01' Tahoe with the same problem.... about 7 yrs ago. It was still under warranty at the time and If I remember correctly, they didn't replace any parts, it was just a matter of re-programing one of the computers, hour job at most if I remeber correctly. I know this probably wont help you much because yours is most likley not under warranty and your looking for a DIY solution. I thinks it's going to be a dealer fix because of a computer issue. I highly doubt the dealer will still have the info when they fixed it but I'll check, if they do I'll get back to you.
Scott, here's another thing you may want to consider. I see you've already checked the in/out temp at the firewall from the heater core. Along with my other problem stated above, a few years later I also had a partially plugged heater core. If I remember correctly, the out line was much more cooler than the in line. All I did was a "reverse flush" through the core. I pulled the two lines going into the core and somehow hooked up a garden hose to the out line (dont remember how I did it). I installed a temp hose on the in line so I could put it into a 5 gal bucket to see if/what I got out of the core. I did get a few smaller chunks out.... and that was enough to fix the problem. With a hot engine, and with your heat on low or off, your core out line should be almost as hot as your in line..... if not you probably have a plugged core.
Scott, if you'd like to call me and get clarification on this, PM me and I'll shoot you my number.
Scott, here's another thing you may want to consider. I see you've already checked the in/out temp at the firewall from the heater core. Along with my other problem stated above, a few years later I also had a partially plugged heater core. If I remember correctly, the out line was much more cooler than the in line. All I did was a "reverse flush" through the core. I pulled the two lines going into the core and somehow hooked up a garden hose to the out line (dont remember how I did it). I installed a temp hose on the in line so I could put it into a 5 gal bucket to see if/what I got out of the core. I did get a few smaller chunks out.... and that was enough to fix the problem. With a hot engine, and with your heat on low or off, your core out line should be almost as hot as your in line..... if not you probably have a plugged core.
Scott, if you'd like to call me and get clarification on this, PM me and I'll shoot you my number.
Last edited by liecheck; November 28th, 2010 at 12:23 PM. Reason: Added info
December 1st, 2010, 1:12 PM
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I had an 01' Tahoe with the same problem.... about 7 yrs ago. It was still under warranty at the time and If I remember correctly, they didn't replace any parts, it was just a matter of re-programing one of the computers, hour job at most if I remeber correctly. I know this probably wont help you much because yours is most likley not under warranty and your looking for a DIY solution. I thinks it's going to be a dealer fix because of a computer issue. I highly doubt the dealer will still have the info when they fixed it but I'll check, if they do I'll get back to you.
Scott, here's another thing you may want to consider. I see you've already checked the in/out temp at the firewall from the heater core. Along with my other problem stated above, a few years later I also had a partially plugged heater core. If I remember correctly, the out line was much more cooler than the in line. All I did was a "reverse flush" through the core. I pulled the two lines going into the core and somehow hooked up a garden hose to the out line (dont remember how I did it). I installed a temp hose on the in line so I could put it into a 5 gal bucket to see if/what I got out of the core. I did get a few smaller chunks out.... and that was enough to fix the problem. With a hot engine, and with your heat on low or off, your core out line should be almost as hot as your in line..... if not you probably have a plugged core.
Scott, if you'd like to call me and get clarification on this, PM me and I'll shoot you my number.
Scott, here's another thing you may want to consider. I see you've already checked the in/out temp at the firewall from the heater core. Along with my other problem stated above, a few years later I also had a partially plugged heater core. If I remember correctly, the out line was much more cooler than the in line. All I did was a "reverse flush" through the core. I pulled the two lines going into the core and somehow hooked up a garden hose to the out line (dont remember how I did it). I installed a temp hose on the in line so I could put it into a 5 gal bucket to see if/what I got out of the core. I did get a few smaller chunks out.... and that was enough to fix the problem. With a hot engine, and with your heat on low or off, your core out line should be almost as hot as your in line..... if not you probably have a plugged core.
Scott, if you'd like to call me and get clarification on this, PM me and I'll shoot you my number.
My 1st reaction was to go and flush the core but the line temperature backed me off that approach.
I stop at the same place for my morning coffee. There is a huge Chevy dealer next door and one of the techs was in so I explained the issue and he said likely a programming issue.
So he actually suggested disconnecting the battery and touching the two battery cables together for 10 seconds.
Still mulling that over, not sure if it was a helpful suggestion or a way to drum up some business from the guy asking for free advice.
December 2nd, 2010, 12:37 PM
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I'd give it a shot if it were my truck. When you start it up you may notice it wont idle for sh*t.... and you may even have to give it gas for the first 10 seconds or so to keep it running until the computers catch up because they've been completely drained of power.
December 24th, 2010, 10:00 AM
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Resolution?
Scott, Did you fix your problem? i have the exact same problem with an 01 Tahoe. Heat in the back, cold in the front. I took off the blend door on the passenger side and it moves back and forth when I switch from cold to heat and back, but it is not a fluid movement. It moves a bit and stops, then moves a little bit more and stops. It eventually gets to the other side and back again. When I put it on, it doesn't look like it is moving all the way back and forth. I'm thinking about ordering a new part to see if that fixes my problem.
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December 24th, 2010, 10:48 PM
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I had a similar problem
My heat quit, inlet hose hotter than outlet on the core, pulled hoses, put inlet in a jug to gather evidence, poured water in outlet and followed it with a blast from the air compresser, was amazed with the chunks that came spewing out and reassembled and the heater now rocks. That is what happened to me (and my brother's 2000).
January 12th, 2011, 10:16 PM
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Scott, Did you fix your problem? i have the exact same problem with an 01 Tahoe. Heat in the back, cold in the front. I took off the blend door on the passenger side and it moves back and forth when I switch from cold to heat and back, but it is not a fluid movement. It moves a bit and stops, then moves a little bit more and stops. It eventually gets to the other side and back again. When I put it on, it doesn't look like it is moving all the way back and forth. I'm thinking about ordering a new part to see if that fixes my problem.
If I remember correctly, those motors are supposed to move in small segments like that. Your blend door motor is probably good.
January 13th, 2011, 8:21 AM
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My heat quit, inlet hose hotter than outlet on the core, pulled hoses, put inlet in a jug to gather evidence, poured water in outlet and followed it with a blast from the air compresser, was amazed with the chunks that came spewing out and reassembled and the heater now rocks. That is what happened to me (and my brother's 2000).