Windshield Defrost Function

[atomicbee]

Hello and Happy Holidays Team Regal!, Well we are finally getting the much needed rain and snow in the mountains in Southern California and I was wondering what is the quickest setting to defrost the windshield? I have pushed the defrost button and increased the temperature to about 77 but it takes some time to clear the windshield so does raising the heat setting to Max the quickest solution? East Coast Regal Eagles are already dealing with the cold winter so maybe they can share some thoughts on this subject.😎

 

[MikeC725]

Yep, try setting it to the max (90*F?). Or you can solve the whole problem by just parking inside......😉 They do make frost windshield covers............

 

[ZoomZoom Diva]

Which defrost button are you pushing, the one above the vent button or the one to the left? You will want to use the one to the left for maximum defrost. This should also turn the A/C on if the temperature is above 40 degrees (not specified in manual, but how most cars work). I have found the defrosting/defogging works very well, though the higher the fan speed and the climate temperature setting, the faster it should work.

 

[atomicbee]

yes the button to the left,but you have to make sure the passenger temperature is in the Sync mode or 1 side will clear faster than the another. I don"t see the reason why the AC has to be on to direct heat to the windshield,with all of my other cars I just slide the knob to the right (heat) and adjust the fan- my 68 Camaro windshield clears faster then the new Regal....GM made good cars in the 60s hence why I"am still driving her (Betty) for the last 23 years.

 

[Walt G]

The A/C comes on to dry the air so you don't 'fog' the inside while you're trying to 'defrost' the outside. But the A/C can only bring the air temperature down to just above freezing (else the evaporator could freeze up), so if it's already that cold out, which is usually the case when defrosting is needed, it won't run.

With an automatic system like we have, you really shouldn't have to adjust the temperature setting to defrost (or warm up the inside of the car) faster. It's not the setting for the temperature of the air coming out of the ducts, it's the setting for the cabin temperature when the system will turn itself 'off' (or to low), much like the thermostat in your house. The system should run at 'full power' (as hot as the outlet ducts can be) until it hits your interior cabin temperature set point. The temperature inside the car should therefore rise at the same rate in either case, and just stop rising sooner if you've got the temperature setting lower. I'd hope your windshield is clear long before your interior hits 90F or 70F, so that setting shouldn't affect defrost time. I guess if you're hitting your target interior temperature and the window is still frosted, the higher temperature setting would help.

If you're finding that the defrost time (or cabin warm-up time) is affected by the temperature setpoint of the automatic system, then GM did a pretty lousy job of calibrating their system... which is quite possible.

 

[Michiganss]

I don"t see the reason why the AC has to be on to direct heat to the windshield, with all of my other cars I just slide the knob to the right (heat) and adjust the fan.

Normally, air conditioning (A/C) is used in the warmer times of the year, and in the winter months the A/C is hardly used at all. This causes problems for the compressor when the A/C is turned on at the first sign of a warm day.

Contained in the refrigerant is a small amount of oil which is circulated along with the refrigerant. This oil is used to lubricate the bearings of the compressor. If the A/C system was not used during the winter months, the bearings of the compressor could seize and that means an expensive compressor re-build.

So, in order for the compressor to be supplied with oil on a regular basis, the A/C compressor is cycled in the defrost mode...which is regularly used in the winter months. Plus, the addition of 'conditioned' or dryer air helps defrost the windows.

It's been this way for decades you just may not have ever noticed it.

 

[Walt G]

I'm not 100% sure on this, but I don't think the AC compressor on our Regals even have a clutch on them. I think they run all the time. But there is a solenoid controlled orifice so that the system can still be turned off , by blocking the flow, despite the compressor always turning. So the lube problem is solved that way.

 

[Walt G]

Found these tid-bits in the service manual... if I can manage to post a couple of pictures...

 

[ZoomZoom Diva]

I haven't tried using the automatic functions as I have generally found they do not direct the air the way I want it directed, particularly the penchant for putting all the air to floor when trying to warm the car. I would rather have heated air hit me all over to make me comfortable and worry about the overall cabin temp later. I do like that air car go to the floor, the dash, and the defrost all at once.

If the AUTO function is off, the temperature range normally acts similarly to a Cold/Hot control on a non-automatic system... and that appears to be the case so far with the Regal.

 

[atomicbee]

I"am testing the other button on the upper right hand(Win-defrost/floor) and I can feel some heat coming up without putting on the fan, once I put the fan on the AC button lights up and it seems to clear a little faster. I have had this car since Nov 13 with about 5,800 miles so my daily usage might be a factor in my inexperience with all the features, I do appreciate everyone's input on this subject!

 

[nizerims]