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I am having heater issues on my 95 Cirrus with 2.5 V6 engine. Last night it was below 20 degrees outside, and the heater wasn't producing air hotter than 60 degrees or so. Brrr. I checked to see if the heater core was possibly clogged. Then I came accross something new to me different from any other car I have worked on. Normally, there is a valve that turns off the coolant flow to the heater core when heat isn't selected. On my car however, BOTH hoses on the heater core were equally as hot as the engine when the thermostat knob was on cold. When I selected heat and turned the fan on high, I observed that one of the hoses had cooled down, but not as much as I expected since it was so cold outside. So... how does this system work? Is there not a valve that turns off the coolant, or is something wrong? Also, air flow greatly decreases when heat is selected. It's weird, but air doesn't come shooting out of the vents on heat like it does cold. Someone enlighten me please. Winter is starting here. HELP! Thanks :)
 

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here is an excerpt from the HVAC Portion of my Digital 1997 FSM:
MAXIMUM HEATER OUTPUT: TEST AND
ACTION
Engine coolant is provided to the heater system by
two 16 mm (5/8 inch inside diameter) heater hoses.
With engine idling at normal running temperature,
set the control to maximum heat, floor, and high
blower setting. Using a test thermometer, check the
air temperature coming from the floor outlets, refer
to Temperature Reference chart.
If the floor outlet air temperature is insufficient,
refer to Group 7, Engine Cooling for specifications.
Both heater hoses should be HOT to the touch (coolant
return hose should be slightly cooler than the
supply hose). If coolant return hose is much cooler
than the supply hose, locate and repair engine coolant
flow obstruction in heater system.
Just my 2 Cents.
 

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Discussion Starter #3
How do you get the digital version of the factory service manual? All I found was paperback on EBay... Thanks for your reply. So, assuming the coolant pipes feel okay according to your information, why could it be so cold coming out of the vents?
 

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How do you get the digital version of the factory service manual? All I found was paperback on EBay... Thanks for your reply. So, assuming the coolant pipes feel okay according to your information, why could it be so cold coming out of the vents?
what are your Air Mode Settings? because in both Defrost modes, the A/C is Turned on Regardless of the A/C Demand Switch to help dehumidify the air coming into the car. if its on Bi-Level, most of the heat is directed to the floor, because as you know; Heat Rises.
 

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Discussion Starter #5
Yeah. Well there wasn't much heat rising lol. Drive the car this morning and same story. It wasn't very humid outside so not much humidity collected on the windshield. So I had the functions on floor+vent. AC off. Clutch wasn't engaging either, so it's not on when it's not supposed to be. I checked floor vent temp. 80 degrees coming out at engine full operating temp, and the heater core hoses were too hot to touch for longer than 5 seconds, one being slightly cooler than the other.
 

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Blend door? Hmm. Interesting... How do you get to the blend door to see if its doing its job?
Pull Fuse #5 in the Junction Block for 20 Seconds, it will cause the Blend Door Motor to run its Calibration Cycle once you reinstall the fuse. (you'll have to reset your Clock as well, because Fuse 5 also provides Power to the Radio Memory, as well as the Interior Lights.)
 

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Discussion Starter #9
Oh. The air direction blend motor? That thing is MESSED up. I read about it back when I got the car and tried the fuse trick many times. It always calibrates incorrectly. The only modes that work right is Face and full Defrost. It doesn't blend correctly in between, and air always blows out of defrost on the other functions. The AC compressor doesn't engage unless a defrost function is selected though like normal. Could this cause problems with how hot the air temp is getting?
 

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The temperature blend door and recirc door are mechanically cable controlled. It could be a cable mis-adjustment or kinking. When moving the temp and recirc dials from endstop-to-endstop, you should hear the doors 'clunk' at either end of their travel. They should swing freely. If the blend door isn't moving to the full-heat position, you won't get the full heater output possible.
The two air direction or mode doors are electronically controlled. It may not calibrate correctly if its movement is stalled during the end-to-end learning travel. The doors or outer gear/lever linkages could be binding or dry of lubricant.
I have also seen door interference from something dropped down into the defroster grille and blocking door movement.
 

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The temperature blend door and recirc door are mechanically cable controlled. It could be a cable mis-adjustment or kinking. When moving the temp and recirc dials from endstop-to-endstop, you should hear the doors 'clunk' at either end of their travel. They should swing freely. If the blend door isn't moving to the full-heat position, you won't get the full heater output possible.
The two air direction or mode doors are electronically controlled. It may not calibrate correctly if its movement is stalled during the end-to-end learning travel. The doors or outer gear/lever linkages could be binding or dry of lubricant.
I have also seen door interference from something dropped down into the defroster grille and blocking door movement.
also, if the Recirc Cable is dry of Lubricant, it WILL Break out the middle of the Control Knob, causing the Recirc Door to stay in Fresh Air or Recirc Mode.
 

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Discussion Starter #12
The temperature blend door and recirc door are mechanically cable controlled. It could be a cable mis-adjustment or kinking. When moving the temp and recirc dials from endstop-to-endstop, you should hear the doors 'clunk' at either end of their travel. They should swing freely. If the blend door isn't moving to the full-heat position, you won't get the full heater output possible.
The two air direction or mode doors are electronically controlled. It may not calibrate correctly if its movement is stalled during the end-to-end learning travel. The doors or outer gear/lever linkages could be binding or dry of lubricant.
I have also seen door interference from something dropped down into the defroster grille and blocking door movement.
also, if the Recirc Cable is dry of Lubricant, it WILL Break out the middle of the Control Knob, causing the Recirc Door to stay in Fresh Air or Recirc Mode.
I will take the lower dash apart to see about lubricating the cables. Any specific lube to use? Otherwise I'll just use 3-in-1 oil or something.

I don't think I have heard them clunk into position before when switching back and forth. Is there a way to look at the air direction motor without removing the whole dash and blower assembly? Thanks guys! Sorry for the delayed reply. I was never notified of any replies like usual.
 

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I will take the lower dash apart to see about lubricating the cables. Any specific lube to use? Otherwise I'll just use 3-in-1 oil or something.

I don't think I have heard them clunk into position before when switching back and forth. Is there a way to look at the air direction motor without removing the whole dash and blower assembly? Thanks guys! Sorry for the delayed reply. I was never notified of any replies like usual.
you can drop the Control Head through where the Cubby hole/Power Point is to access the back of the Control Head to Lubricate the Control Head side of the Temperature Blend/Air Recirc Door Cables (I used White Lithium Grease on my cables; also, I would lubricate the Bevel Gears on the Control Head itself.) the Mode Door Motor is actually viewable after you remove the Driver's side Footwell Duct (you have to remove the two screws that secure the bottom of the knee bolster first, you DON'T have to remove the cluster Hood or the whole Knee bolster to do it.)
 

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Discussion Starter #14
Okay sounds good. Will reply back after I'm done checking it out. I've also discovered that the gears on the back of the control head are greased quite well already.
 

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Discussion Starter #15
Well it managed to get warm enough outside for me to check, and it appears that the blend door is opening and closing all the way with the turning of the thermostat. There's also restricted airflow on the heat side vs the cold side. Any suggestions? Thanks
 

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Discussion Starter #16
Sorry for the delayed replies! So, I checked the cables, and it turns out that the blend door cable has streched over the years and is also somewhat bent. It doesn't move the blend door according to the thermostat setting, it's not engaging full heat or full cold when the knob is turned lock-to-lock. So, anyone know where to order a new one? This seems to be the least of my problems, after a storm the vents smell horrible, like a musty wet car smell. I think water is leaking into the air box, and my passenger side vents have quit blowing air all together. Any tips on taking the dashboard out and removing the air box to work on it and perhaps clean it out? Thanks guys!
 
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