Climate Control
#3
03-08-2006, 05:09 PM
RE: Climate Control
I've taken it to the shop and all they want to do is replace everything rather than diagnose the problem...their estimate was over 2K...I'm looking for some direction on how to do it myself. Has anyone else experienced this?
#4
03-08-2006, 11:44 PM
RE: Climate Control
i assume blower is functional...right?
can you elaborate more about the problem?
no cooling?
flap don't work?
can you elaborate more about the problem?
no cooling?
flap don't work?
#5
03-10-2006, 04:25 AM
RE: Climate Control 300CD
Thank you. I have attached an image of the climate control unit. The top push button turns on the defroster. When I press the top button and the engine is warm, warm air blows from the defroster vents. The second, third a fourth push buttons from the top rest are for the heater (various mixtures). When I press them...nothing...no blower no heat. The bottom push button turns all off. This control unit is over $500.00 and do not wish to replace. Any experience with this issue?
Thank you
[IMG]local://upfiles/11242/E416A60646C44C409AEFCEA68064DC11.jpg[/IMG]
Thank you
[IMG]local://upfiles/11242/E416A60646C44C409AEFCEA68064DC11.jpg[/IMG]
#6
03-10-2006, 05:40 AM
RE: Climate Control 300CD
not really difficult to troubleshoot.
am on weekend. remind me next week.
am on weekend. remind me next week.
#9
03-16-2006, 01:01 AM
RE: Climate Control
I had a similar problem on an older 300d ('79)
I fixed the problem (for free) myself.
The servo is the weakest link, and the gearmotor inside it is the brains of the whole system. Mine had a good motor, but it was stuck-wouldn't move.
The gear motor does three thing all at the same time:
1) Opens, closes and reguates how much hot water from the cooling system flow to the heater core inside the car. (It operates a valve)
2) rotates another valve that contols all the vaccum controls for the HVAC system. This valve decides where the blower air comes out inside your car.
3) It operates a lever contact arm that controls blower speed, a/c compressor on and off.
Here's how it works:
the thermostat inside the car reads the temperature inside the car. It looks at the temperature dial setting that you chose. It compares the two to see if cooling or heat is required to meet your desired setting. This signal is sent to the electronic regulator behind the glove box as an input.
The electronic regulator behind the glove box sends voltage to the servo motor as an output (usually up to 4 volts+ or 4 volts -) depending on whether heat or cool is required. As the servo operates, a potentiometer signal coming back from the servo tells the controller what the servo did. If for instance, you needed a little bit of heat, maybe only 2 volts vould go to the servo gearmotor. As the gearmotor turns, the 2 volts becomes 1-1/2, then one, and finally 0 volts meaning the servo did what the controller told it to, and stopped at that setting as commanded. The system now measures the temp inside the car, and compares it to the temp you set the dial for, and the process starts all over.
To test the unit manually, go under the hood and unplug the electric and vaccum connectors from the servo. Remove the top plastic cover from the servo, and expose the copper tabs that the electrical connector harness you just unpluged hook to. Two of these tabs have a small guage wire hooked to them that goes down into the bottom of the servo. These two leads run the gearmotor. (not the two wires from the potentiometer) If you put + volts on one and - volts on the other, it turns in one direction (say heat) if you reverse polarity, it turns the other way (AC) the more the motor turns, the hotter or colder the system works. Connect a 6 volt battery (or in a pinch use 3 "D" batteries in series-4.5 volts) to the tabs with the motor leads soldered to them. Don't move the motor too much, just see if it turns. Reverse the polarity and make sure it turns the other way. You can't see the motor, but look closely at the potentiometer to see if it is turning-it turns very slowly in both directions.
While you are operating the servo manually with your 6 volt battery, you can go inside the car to see what is happening, but first, unplug the connector from the regulator behind the glove box. After you do that, you can hook up the vaccum and electrical harness to the servo. Don't run the servo with your battery if the regulator behind the glove box is plugged in-you will backfeed the regulator.
In my car, the servo motor was stuck. The 6 volt battery got the gearmotor working again, but I still couldn't get the heat/AC to work right. I disconnected my 6 volt battery, then plugged the regulator back in, hooked up a digital voltmeter to the servo gear motor leads to see what was happening. I was getting no voltage to the leads. I took the regulator (behind the glovebox) out of the car, and opened it up. It just needed to be resoldered. I soldered it, reinstalled it, checked again for voltage to the gearmotor leads, and was good to go.
While using the voltmeter, sit in the car and move the temp dial up and down. You should see the voltage go up, then come back to zero as the servo turns. When you turn the dial the other way, you should see the polarity reverse, go up then back to zero.
If you do these simple tests, you can use the process of elimination to determine if you have a bad contol panel, bad servo, or bad regulator.
John
I fixed the problem (for free) myself.
The servo is the weakest link, and the gearmotor inside it is the brains of the whole system. Mine had a good motor, but it was stuck-wouldn't move.
The gear motor does three thing all at the same time:
1) Opens, closes and reguates how much hot water from the cooling system flow to the heater core inside the car. (It operates a valve)
2) rotates another valve that contols all the vaccum controls for the HVAC system. This valve decides where the blower air comes out inside your car.
3) It operates a lever contact arm that controls blower speed, a/c compressor on and off.
Here's how it works:
the thermostat inside the car reads the temperature inside the car. It looks at the temperature dial setting that you chose. It compares the two to see if cooling or heat is required to meet your desired setting. This signal is sent to the electronic regulator behind the glove box as an input.
The electronic regulator behind the glove box sends voltage to the servo motor as an output (usually up to 4 volts+ or 4 volts -) depending on whether heat or cool is required. As the servo operates, a potentiometer signal coming back from the servo tells the controller what the servo did. If for instance, you needed a little bit of heat, maybe only 2 volts vould go to the servo gearmotor. As the gearmotor turns, the 2 volts becomes 1-1/2, then one, and finally 0 volts meaning the servo did what the controller told it to, and stopped at that setting as commanded. The system now measures the temp inside the car, and compares it to the temp you set the dial for, and the process starts all over.
To test the unit manually, go under the hood and unplug the electric and vaccum connectors from the servo. Remove the top plastic cover from the servo, and expose the copper tabs that the electrical connector harness you just unpluged hook to. Two of these tabs have a small guage wire hooked to them that goes down into the bottom of the servo. These two leads run the gearmotor. (not the two wires from the potentiometer) If you put + volts on one and - volts on the other, it turns in one direction (say heat) if you reverse polarity, it turns the other way (AC) the more the motor turns, the hotter or colder the system works. Connect a 6 volt battery (or in a pinch use 3 "D" batteries in series-4.5 volts) to the tabs with the motor leads soldered to them. Don't move the motor too much, just see if it turns. Reverse the polarity and make sure it turns the other way. You can't see the motor, but look closely at the potentiometer to see if it is turning-it turns very slowly in both directions.
While you are operating the servo manually with your 6 volt battery, you can go inside the car to see what is happening, but first, unplug the connector from the regulator behind the glove box. After you do that, you can hook up the vaccum and electrical harness to the servo. Don't run the servo with your battery if the regulator behind the glove box is plugged in-you will backfeed the regulator.
In my car, the servo motor was stuck. The 6 volt battery got the gearmotor working again, but I still couldn't get the heat/AC to work right. I disconnected my 6 volt battery, then plugged the regulator back in, hooked up a digital voltmeter to the servo gear motor leads to see what was happening. I was getting no voltage to the leads. I took the regulator (behind the glovebox) out of the car, and opened it up. It just needed to be resoldered. I soldered it, reinstalled it, checked again for voltage to the gearmotor leads, and was good to go.
While using the voltmeter, sit in the car and move the temp dial up and down. You should see the voltage go up, then come back to zero as the servo turns. When you turn the dial the other way, you should see the polarity reverse, go up then back to zero.
If you do these simple tests, you can use the process of elimination to determine if you have a bad contol panel, bad servo, or bad regulator.
John
#10
03-30-2006, 11:10 PM
RE: Climate Control
If you ever need a rebuilt climate control servo for the vertical button system on the pre-1981 cars, click here to see a source for a well built replacement unit:
http://www.duricy.com/~imperialist/A.../autotemp.html
Don't let the Chrysler Imperial stuff fool you, it's the same servo.
John
http://www.duricy.com/~imperialist/A.../autotemp.html
Don't let the Chrysler Imperial stuff fool you, it's the same servo.
John
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