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Discussion Starter · #1 ·
Well, I’m getting my 1989 Bentley running much better. I found a shop that rebuilt the Bosch fuel injection at significant cost, but at least it runs well now. I need a thermal times switch. Anyone know the best source for this?
Thanks!
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Discussion Starter · #3 ·
The switch that I have been looking at is on top of the thermostat. It seems to operate just the radiator cooling fans and works fine. My cold start modular doesn’t seem to work. Car hates to start when cold. My Aircon fans don’t come on. It sounds like a thermal time switch which must be someplace else?? Car drives great now and will start with just a half ounce of gasoline poured into the intake before cranking. it then starts and idle‘s perfectly. Confusing. Thank you for any thoughts!
 

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If you are refering to your A/C fans in the dash board not turning on then there could be several reasons why.
The time delay (actually temp delay 44 degrees) switch only opens when the engine coolant gets warm so to eliminate that switch and see if it is causing your NO FANS just disconnect it. If the fans now work that is the issue. If they don't work now you are into a much bigger problem of trouble shooting why they don't work.
 

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I think that he's talking about the Thermo Time Switch which is used to ground the cold start injector when required to add extra fuel when starting.

If so, anywhere that supplies Mercedes Benz or other German cars like Audi, Porsche and German Fords will have it. Check the part #.
 

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Discussion Starter · #6 ·
If you are refering to your A/C fans in the dash board not turning on.......
Thank you for your response!
Where is the temp delay switch?
There is a temp switch on the top of the thermostat. Removing those two wires and patching them together makes the radiator fans run. So it is a switch only meant to prevent engine overheat. So this can’t be the temp delay switch…
 

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There are condensor cooling fans and HVAC duct fans. Both have different sensors/switches. The front fans are designed primarily to keep air moving in front of the condenser when the car is not moving and has no "connection" to the dash fans.
 

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The 44 deg sensor on the thermostat neck triggers the HVAC ECU when the coolant temp is at proper temp allowing the dash fans to work. If this sensor is bad they will not turn on. Pull the 2 wire connector off and they should work, thus over riding the sensor.
 

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Please explain which fans you are having trouble with
The fans on the radiator for cooling the engine OR
the fans inside the cabin of the car that blow cold air from the air conditioning system?
 

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There are 3 sensors on the thermostat housing if you have fuel injection: there is one to the ECU, one for the HVAC 44 deg sensor and one for the front condenser fans.
 

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Look at the parts pic. Pull off connector UE43063 Notice the description is HVAC fans

FYI Almost every car from 1977 with the new HVAC 2 zone climate control has this switch. It is not a "thermal time switch" Simply a thermal switch to turn on cabin fans once the coolant reaches proper temp.
 

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Discussion Starter · #17 ·
I found it! Underneath everything. Unhooked it and no changes. The system makes blend door sounds but the HVAC fans don’t come on.
If I ground individual relays the fans work and so can get heat but no AC. So the relays seem
Ok. The temp select does seem to work in that case sending out either warm air or slightly cooler air.
 

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I certainly yield to the experts here, however, this is how I sorted my HVAC. Had the same issue as you did with the 44 degree sensor, but also only a low fan speed regardless of settings. What I learned was that voltage can be lost across the fan relays. Since all my relays were original, I replaced every under hood relay from new ones ordered at Albers. Completely solved my issue and then had all fan speeds and proper operation of the HVAC. Should have just tested each, but felt it was good maintenance.

If that didn't work, my next plan was to rent the HVAC test box from Flying Spares, (RH9884LOAN)
 
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