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2000 S10 Blazer - no heat
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wally107
New User
Nov 19, 2008, 8:15 AM
Post #1 of 8
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2000 S10 Blazer - no heat
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At my wits end - coming to the experts.
2000 S10 Blazer 4.3L V6 LT (loaded) 130K miles
Electronic Climate Control
Began having "no heat" probs last fall. So far: flushed (numerous times), 2 new thermostats, new water pump (leaky weep hole).
The only thing that seems to work is flushing the heater core. However... it only blows heat for approx 30 mins, then slowly cools off, finally blowing cold. When flushing the core, we see NO chunks, gook, etc. Appears to flow clear. I honestly don't think it's a heater core problem.
Is it possible that disconnecting the heater core hoses "temporarily" opens the accuator door, then it slowly closes?
I realize I'm grasping at straws, but running out of ideas. HELP!!
P.S. Been looking at all of the related posts, and just wanted to add: both heater core hoses are toasty-warm both prior to and after the flush, and as I mentioned, I've never seen anything but AF or clear water come out - hence I'm leaning away from a heater core issue. Also, the temp has always been nominal (200-210) and AF level is good. We've been chasing this for over a year, so I'm starting to lean towards a control/valve problem. Any help would be greatly appreciated!
Hope y'all don't mind - in despiration I also posted this on ACSOURCE. Thanx!
(This post was edited by wally107 on Nov 19, 2008, 10:50 AM)
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Loren Champlain Sr
Veteran
/ Moderator
Nov 19, 2008, 4:32 PM
Post #2 of 8
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Re: 2000 S10 Blazer - no heat
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Hopefully someone more knowledgeable (Like Tom) will jump in, here, but it sounds like a blend door problem. The heater hoses, in and out, should be of equal temp at all times. The blend doors open and close to allow heat and to direct it's flow. Could be a lazy blend door actuator?
Loren
SW Washington
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Nov 19, 2008, 5:36 PM
Post #3 of 8
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Re: 2000 S10 Blazer - no heat
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wally107 - I'm glad you took it to ACSOURCE - the link is in my sign off here and I saw you there and still don't know what for sure as if we ever can.
I think the blend door is electrically actuated and if it can it's "home" position would be to default to cold rather than warm/hot air.
I'm totally confused why it can start off ok and slowly fade like you mentioned. There's a bunch of A/C geeks at ACSOURCE (Gosh - they'll kill me for saying that!) - the strange stuff shows up there.
Wouldn't you figure that if this can start off working it would at least stay there? That's what screwed me up.
I think you said this was ATC (forget this if not) and sometimes junk can block the sensor(s) so it thinks it's done cooking you and backs off. Clear junk, stickers, decals added or whatevers off dash if that's the case??
T
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wally107
New User
Nov 20, 2008, 5:26 AM
Post #4 of 8
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Re: 2000 S10 Blazer - no heat
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Tom & Land - thanx for your quick replys. Can't tell you how comforting it is to know the pros are as stumped as I am.
Probably insignificant, but last night I tried hitting the RECIRC button - and it warmed up considerably. I suppose this only makes sense, since it's then re-heating the same air (and blocking out the outside air). Again, probably not significant, but thought I'd mention it.
Like you guys, I've never heard of a blend door/actuator acting like this - but it seems like the logical next thing to check. I think the fact that it heats up right after I flush the heater core is significant - I'm just not sure how.
Anyway - next question: Is the glove box the best access to the blend door? From everything I've read here and at ACSOURCE it seems so. Any advice?
Thanx again for all your help!
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Nov 20, 2008, 7:47 AM
Post #5 of 8
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Re: 2000 S10 Blazer - no heat
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http://www.autozone.com/...eId=0900c152800a5d7c
Wally - that link was the closest I could get as I said at ACSOURCE the info led to the full size vehicles. If you get into that site - see if you can steer it to your vehicle as info is released for public view in there. If all fails I'd get the version of AllData for your exact vehicle which costs about $25 bucks but would be a monster help about now. I don't have the full programs. Some libraries do! Check locally if you can.
Ok: There's a diagram of the actuator and a heater control (water) valve from that link but it keeps taking me to full size vehicles?? If you have a inline heater control valve that looks like that on heater inlet hose then I'd try applying vacuum with hand pump to that sucker just to see what it does!
You can see the rods with their funky fangled springs and clips that connect them in top diagram. They break rather easily and can partially work! Remember these and most have a "home" base setting when everything is off to default to in failures.
Seems like this is what's happening and why is the question/problem??
T
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wally107
New User
Nov 20, 2008, 9:03 AM
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Re: 2000 S10 Blazer - no heat
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Tom - now we're gettin' somewhere (uhh, I think...)
I've finagled with the heater hoses coming out of the firewall, and I don't recall seeing that type of control valve - but then again, I haven't been looking for it. I'll check again.
I've dabbled with Alldata in the past - I'll dabble some more.
Somewhere either here or on ACSOURCE, someone mentioned removing the "RDO fuse", reinstalling it, then turning the ignition ON to reset the actuator. Have you ever heard of that? It sounds similar (sort of) to what the Autozone guidance refers to.
Ref the acuator rods/springs: do you know if I can access these thru the glove box?
Again - can't thank you enough. Feels like my wheels are no longer spinning - starting to get some traction!
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wally107
New User
Nov 20, 2008, 12:41 PM
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Re: 2000 S10 Blazer - no heat
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Tom - "dashboard diving" - LOL!! You're a braver man than I. The only part of me I want to put under the dash is my feets! Hence, I can say I've made no forays into, under, nor around the dash (so far). So if one of the rods/doors is screwed up...I'm innocent.
I have been sure to keep the mode & fan knobs out of the AUTO position - so the ATC function really doesn't figure into this (I don't think).
If I understand this, the temp knob (in the middle) only controls the amount of coolant allowed to flow through the heater core. Low temp=no fluid thru core, High temp=lots of fluid thru core. All of which is "metered" by the control valve (which may be located somewhere along the smaller hose). Do I have that right?
I figured the hot air should overwhelm the fresh/outside air, regardless of temp - but it did help a little, so I thought I'd mention it.
I changed the battery some time ago - I don't recall if was the same time that this "no heat" began. Maybe I'll try to disconnect it - just for giggles.
Thanx again... Wally
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