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Temperature control knob turns but doesn't change temp.
I just bought a 1991 900S 16V w/ 167K and am in the process of sorting thru the probs. Temp control knob turns freely, but does not do anything to alter temp. I pulled the stereo and the rod behind the knob turns, but don't know where it comes thru the firewall to check there. Suggestions? Fan control, air flow change control works, a/c control works, just not getting heat/temp change from knob. Thanks!!
Re: temperature control knob turns but doesn't change...
The heater control valve is visible through the speaker cut-out; it's at the end of the plastic heater control rod, inside the car - not on the other side of the firewall! It's connected to the valve with a plastic "universal joint".
Check that the valve is actually being turned by the rod. The connection might not be good (pulled apart or broken), and or the valve might be stuck.
Re: temperature control knob turns but doesn't change...
Hi there. Is the car overheating at all? Do you have an antifreeze smell blowing in the vents or antifreeze on the floor of the car? If so these are signs your heater core is shot. If not, it is probably the actuator motor on the side of your hvac unit under the dash. Locate your actuator unit and take it off, couple screws and a wire clip, and turn the knob it hooks to manualy. This should make the air temp change if your core is good. Hope this helps.
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Hi Sharon, I'm glad to help. Your 2000 year doesn't have a motor for the temp door. It operated by a cable running from the control head to the temp door and you work it manually. If you can't control the temperature from hot to cold, sometimes the cable come off or breaks. Here how you can see the cable to see if its working. Remove the radio and right behind it you will see the cable attached to the door, while watching it move the temp lever from hot to cold and watch it. If it is moving then its most likely out of ajustment. If it is not moving, then you'll need a new cable. Just in case it is moving, I'm attaching the instruction on how to adjust it below. Hope this helps and have an awesome day Sharon!
TEMPERATURE CONTROL CABLE
Any time the heater-A/C control or the temperature control cable are removed and/or replaced, the following procedure must be performed.
The temperature control cable housing and core must be installed at both the heater-A/C control and the heater-A/C housing ends, and the heater-A/C control must be installed in the instrument panel. See Heater-A/C Control and Temperature Control Cable in the Removal and Installation section of this group for the procedures.
Rotate the temperature control knob on the heater-A/C control so that the knob pointer is in the 12 o'clock position.
Pull the temperature control knob straight out from the heater-A/C control base until the perimeter of the knob (not the knob pointer) protrudes about 6 millimeters (0.25 inch) from the face of the control base.
Rotate the temperature control knob to the 1 o'clock position. Push in on the knob slightly and continue rotating the knob to its full clockwise stop. The knob pointer should be aimed at a position about 8 millimeters (0.315 inch) beyond the end of the graduated red strobe temperature control graphic on the face of the heater-A/C control base. If the knob is not pointed to the correct position, go back to Step 2 and repeat the adjustment procedure.
Rotate the temperature control knob counterclockwise until the knob pointer is in the 12 o'clock position again.
Push the temperature control knob straight in towards the heater-A/C control base until the perimeter of the knob (not the knob pointer) is flush with the face of the heater-A/C control base.
Rotate the knob to its full clockwise stop again. The knob pointer should be aimed at the end of the graduated red strobe temperature control graphic on the face of the heater-A/C control base. If OK, go to Step 8. If not OK, go back to Step 2.
Rotate the knob to its full counterclockwise stop and release the knob. If the knob springs back from the counterclockwise stop, the self-adjuster clip that secures the temperature control cable to the blend-air door lever is improperly installed. See Temperature Control Cable in the Removal and Installation section of this group for the procedures. If the knob does not spring back, the temperature control cable adjustment is complete.
No one ever said new means good. Try another thermostat. Make sure it is the recommended temp for the vehicle. I would spend the extra money to buy a dealer thermostat. What controls temp is restriction of flow thru the system until a set temperature is reached and the thermostat opens. Has to be a thermostat.
Sorry for your troubles ,
Temperature Hand in dash reading NORMAL ?
Does it Turn Blue to Red if so is do you feel friction or restraint like your turning something rather than freewheeling (smooth fast turning) or Digital and or does it show that it should be warm and not cold ?
Does the TEMP change at all(even the least little bit could narrow the results down) when knob is turned?
POSSIBLE - The Actuator/Motor that switches the VENTS very well could be BAD , Temperature Switch / Climate Control Switch (hot to cold could be broke at the base and only allowing the knob to turn and not in the switch ) Thermostat may be stuck open (keeping the engine running cool and smooth but no heat , maybe just a slight TEMP change when switched from Cold to Hot ). The A/C Switch is pushed in or turned on or broke and is stuck ON
FIXES - 1st- Check FUSES - If Temp HAND Reads Normal it not your THERMOSTAT. - Change the Control Switch / Temp switch - Check A/C Button/Knob . AUTOZONE is my place of business they PRICE MATCH AS WELL!
Hope this Helps , Flaming Ratchets Auto Repair
This can be caused by a bad controls or bad blend door motor, the door motor and controller will need to be tested to see which is causing the problem,
when you say temp fluctuates what happens? are you using the a/c and you turn temp down one click and it goes to hot ? Is the temp going from hot to cold hot to cold as you drive?
You need to repair the heater core with a soldering gun.
If you do not have heat, or only have heat, IMHO it is most likey the AC/heater control unit. This is the part which has the AC/heat control buttons and knobs.
Easy Diagnosis: The easiest way to verify this is to turn on the radio, press and hold the power on/off button and press and hold the scan-up button for a second (full second). The word "A/C TEMP" should appear on the left of the display and a number from 0 to 16 on the right. I suspect yours will have the number 0 (or 16 if heating only problem) displayed no matter where you turn the temperature control knob. If this is the case you could turn the temp. knob to full heat and see if it goes to 16 after pushing down or to the right on the knob. In a working system, the number moves evenly in increments of 1, from 0 to 16 as you turn the temperature knob.
Easy Fix: I was able to take mine out and solder 3 loose connections to fix it.
The beginning steps are the same as for any radio removal procedure and check for loose connections.
I'm glad I could help. I'm reposting the solution below in case anyone needs it in the future. Please be sure to rate it for me!
Pull the temperature knob off and verify the thin 12mm nut is installed
and tight behind it. I have seen several of these loosen up allowing
the knob to turn but intermittently have no effect on temperature.
1) The temperature shaft retention nut is loose behind the knob
2.) The wires to the potentiometer part of the temperature may be broken.
Either one is common to this vehicle. The replacement of the AC controller is about 900 dollars. If the wires are broken, they can easily be reattached to the circuit board via soldering. What you would have to do is remove the control box from the dash, and disassemble it. Once the unit is apart, there are 3 wires from the temp knob to the circuit board that need to be re-soldered. The unit CAN be repaired, as opposed to the expense of replacing it.
i remember trying this. if your water pump is faulty. while the engine is off, spin the radiator blade. if it spins, then your pump is out, if it stops immediately, (it has a cluth of sorts) it's ok. also use a lower degree thermostat, like 160 degrees, then it will open sooner.
Thanks for the suggestion. I'll give it a try and let you know.
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