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VikezFan
New User
Nov 4, 2008, 7:58 AM
Post #1 of 5
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'95 Intrepid no heat
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I am working on a '95 intrepid with a 3.3L V6 that only blows luke warm air when heat is on. Flushed heater core both forward and backwards 4 times. Plenty of flow both directions. Both hoses going through the firewall to the heater core get hot now (they weren't before). Still only blows luke warm. Has manual heater controls. Went through diagnostic mode and everything checks out. Checked that blend door actuator was moving. Removed proper fuses for blend door 'calibration' and let sit for 10 mins. Reinstalled fuses and listened to air flow while turning the temperature control listening to the blend door move and the air flow change throughout the entire range. So, as I see it, I have eliminated the heater core, control, and blend door. What am I missing? It still blows luke warm air.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Nov 4, 2008, 8:32 AM
Post #2 of 5
(3370 views)
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Re: '95 Intrepid no heat
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?? Though I already responded this question?? Does raising the idle speed help a lot or at all? I wonder if water flow is adequate - rare but sometimes water pump impellers don't pump as well as intended.
If that was so - higher engine speed would help. That and low fan speed would be markedly warmer than high fan speed with limited hot coolant available - return hose would be much cooler than inlet hose as all the heat was lost. If both are staying about the same it suggests that the flow is adequate.
Does temp of inlet hose get noticably cooler at some point along its route?
T
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VikezFan
New User
Nov 4, 2008, 6:14 PM
Post #3 of 5
(3357 views)
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Re: '95 Intrepid no heat
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The coolant for the engine is good. The thermostat works where it is supposed to and the electric fans turn on and off. The water pump seem to be circulating the fluid also since the engine is not overheating. I hooked to the two short heater hoses to run the flush water through. I could get full flow through with both forward and backwards flushes.
This coolant system overheated badly about a year and a half ago when the head gaskets gave out and exhaust got into the coolant jacket. I replaced the head and intake gaskets on it then. I am not sure the heater has worked right since.
Right now I am leaning towards the air pockets theory. I bled the system through the valve by the thermostat, but I have heard that Intrepid cooling systems are sometimes hard to bleed. What do you think?
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Nov 4, 2008, 11:26 PM
Post #4 of 5
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Re: '95 Intrepid no heat
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http://autoforums.carjunky.com/...;;page=unread#unread
That link was recently locked hopefully to shed light and be improved on discussing the problems of purging air or better said vapor out of a cooling system as it's a problem in many vehicles. Feel free to add to that any experiences you have or suggestions that have worked for you.
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In this case I doubt air or vapor is the direct problem now. Just by nature of "air rises to the top" physics it should have self purged once the system is close enough to maintain a steady temp the rest should just happen thru the cycles of warm ups (expansion) and cool downs (contractions) of the coolant over time.
The question and problem now is to find out where this heat is going. The whole idea of a radiator and a heater core is a smaller version of the radiator needed to cool the engine is to transfer heat.
By nature vapors however hot they are don't carry the caloric value to transfer much vs a liquid and might go thru inlet hot to the touch but leave for return at close to the temp of air that passed thru it.
If a heater hose is warm/hot on the way it is supposed to shed that heat and you should notice outlet temps lower but usually not cold. Heat is abundant in internal combustion engines and actually a waste product of them to be dealt with. The profile of the vehicles are less condusive to allowing simple gravity and convection to adequately move the heated liquid so almost every engine uses a "water pump" to force it along. The heater uses smaller hoses and further away then the primary radiator so that pumping it along is a challenge.
Air doesn't even pump well in the impeller of a standard water pump till it's imersed in just liquid. Take the propeller of a boat as an example of how such a small fan/impeller is useless until it's submerged in water AND how effective it is when it is completely air free - big difference of course.
For whatever reason the heated coolant isn't making it to the right place or the resultant heated air isn't making it to the cabin. In this case it seems like all things have been covered so we need to know where it went. Is the outlet line cooler as evidence of transfer taking place? If there was inadequate flow the outlet temp would be remarkably cooler OR if what passed thru wasn't liquid.
Since we can't see thru the hose we can only go by the temp of the hose as evidence.
Either the flow is inadequate or the heat is being misdirected which would be a blend door issue that seems to be ruled out but all is possible is that the complaint exists.
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If this is one to have a persistant air problem there are some rather extreme measures that have worked. Plain old positioning of the vehcile such that the highest spot is available for air to exit to recovery tanks has worked in some tough cases sometimes by jacking up the car to an extreme.
A problem in the course of getting the air to the top is that a thermostat is nearly airtight and a restriction when closed. Many thermostats have a small notch or a tiny bleed valve on them that can go unoticed and that does need to be known places at the top. In some cases that just don't behave it could be that it wasn't engineered into the thermostat or could be plugged by gasketing or excessive sealer used. In some VERY difficult cases I've drilled the smallest hole to allow for that air to escape even with thermostat closed.
If there was excessive amounts of coolant bypassing the termostat when cold it should be seen as an engine running too cool such as a failed thermostat that doesn't shut tight would demonstrate.
Some thermostats are designed and usually marked if position is important enough with the word "top" or perhaps arrows on it to indicate positioning.
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Ok - Some things that come to mind that could be the proiblem are.....
* Anti-freeze too strong. Carefully adjusting the mix for -25F or so might really help. Note - that lowers the anti-corrosive ability so change intervals should be increased.
* An OE thermostat would rule out a flaw in design of an aftermarket one.
* Maybe a flaw in hoses or gasketing or gasket sealers blocking intended coolant flow.
* Water pump itself may be cavitating unseen but I think this one is a pest to change or remove for inspection but I'll put that on the list.
* It wouldn't take too much of a problem with a blend door in distribution box to screw up the performance. Not sure how best to test that out.
* Maybe there's excessive dirt on the exterior of the core. Maybe that could be seen or cleaned by removing the blower motor and cage. If that sounds like a possibility and access is difficult perhaps blowing air in condensate drain would clear out some debris before a complete dismatle of distribution box to really check it all out.
* There could be lingering problem with the head gasket job.
Do you have any other ideas that might help me/us lead to the correction of this problem?
T
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Loren Champlain Sr
Veteran
/ Moderator
Nov 6, 2008, 2:46 PM
Post #5 of 5
(3341 views)
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Re: '95 Intrepid no heat
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Tom was right on; I'd like to add my input. I've had to do just what Tom said. Run the rig as high as you can, nose first. I use a drive on lift, put the front wheels on it and stand the car on it's rear bumper (not really, but a good visual). Again, like Tom said, it is very rare, but I've also seen impellers slip on the shaft when hot. You'd just about have to remove the thermostat, get the engine hot, then watch for flow, but even then you may not be able to duplicate the symptom. Good luck. Let us know what you find.
Loren
SW Washington
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