QuestionQUESTION: First run in the morning and the fans run which allow the A/C to perform.
Drive awhile and stop for whatever. Get back in after a short stop and no A/C because the aux fans will not run.
Need help.
ANSWER: H.R.
Aux fan?,if you mean the blower in the dash that come on line then there may be a problem with the refrigerant level or thermostat switch in the climate control.
The fan is delayed when there is head buildup until the compressor has had an opportunity to lower the temperature in the evaporator. This process keeps the occupants from being blaster by hot air out of the AC ducts from under the dash and windshield.
I would have the refrigerant level checked first. Low refrigerant will cause short cycling of the the compressor.
Good Luck let me know what you discover.
Rob
---------- FOLLOW-UP ----------
QUESTION: Rob:
No I mean the two fans in front of the radiator. Some times the right fan will run (facing the car) but not the left one. My M-B mechanic said they both have to run for the A/C to operate, but he is does not have an electrical bent.
AnswerOK,
Now we can discuss the possible problems. One fan is controlled by the coolant temperature through a thermostat switch. The second fan is switched on to run continuously anytime the AC operates to additional heat removal to the AC condenser. It may also have a high temperature thermostatic switch to bring in in even it the AC is not engaged when the coolant gets closer to boiling as in traffic or while idling.
I would suspect that something else in the AC system is keeping the fan and compressor from engaging, not the other way around. Is this a R12 or a 134A system?
Have you had the refrigerant checked with gauges. If the refrigerant is low then the dash evaporator may be collecting ice because moisture is remaining on the fins. There is a thermocouple that controls the refrigerant flow through the evaporator and it switched the compressor clutch on and off as needed to maintain flow through the system and cooling. If the couple senses that the temp is cold enough it would switch of the compressor and the aux fan, as in the situation you suggested.
Find an reliable AC service shop and have the refrigerant checked first.
The should be able to extract all the refrigerant into their recovery machine then ad back the proper amount base on the manufactures recommendation. Too much or too little is not good. During the removal, they should be able to pull a vacuum and hold it without it leaking down.
If there is a leak that must be repaired before refrigerant can be replaced. It does not mean that the repair must be done a the recovery shop. If you find a leak that you can repair, they should be willing to allow you to make the repair and have you return to recharge the system, for just a very little additional fee.
I would broach this issue before hiring them to do the diagnostic.
Good Luck Let me know what you find out.
Rob
