Question about Automatic Temp. Control

[MTLFusion2010]

I leave my ATC on Auto and the temperature set to around 22C (~72F). In hot weather, and when starting the car after being left outside, the ATC would start the fan at a high setting and then drop it down as the cabin temperature dropped.

Now that the outside temperature is hovering around freezing, I noticed that when I start my car after the climate control system takes a long-ish time ( a few minutes) to start blowing air through the vents. If I manually control the fan, then it works as expected.

 

Is this normal? Is the system waiting for the coolant temperature to reach an adequate level and avoid blowing cold air into the cabin?

[bbf2530]

I leave my ATC on Auto and the temperature set to around 22C (~72F). In hot weather, and when starting the car after being left outside, the ATC would start the fan at a high setting and then drop it down as the cabin temperature dropped.

Now that the outside temperature is hovering around freezing, I noticed that when I start my car after the climate control system takes a long-ish time ( a few minutes) to start blowing air through the vents. If I manually control the fan, then it works as expected.

 

Is this normal? Is the system waiting for the coolant temperature to reach an adequate level and avoid blowing cold air into the cabin?

 

 

Hi MTL. :D Yes, this is normal. System is designed not to begin blower operation until the engine has reached an operating temperature where it can circulate warm air at the set/desired temperature.

 

Good luck. :beerchug:

Edited November 28, 2010 by bbf2530

[NHFocus]

^ Hit the nail on the head. The ATC is going to keep the blower fans off, so that the heater control valve stays closed. This allows the coolant to circulate in a much smaller loop and heat up faster. Once the closed circuit coolant is warm enough to actually blow hot air the valve opens and allows coolant to circulate through the heater core. When you operate the system manually you'll get 'warm' air out of the vents for a while but it will take the car much longer to reach operating temperature.

Edited December 2, 2010 by NHFocus

[rpreuss]

^ Hit the nail on the head. The ATC is going to keep the blower fans off, so that the heater control valve stays closed. This allows the coolant to circulate in a much smaller loop and heat up faster. Once the closed circuit coolant is warm enough to actually blow hot air the valve opens and allows coolant to circulate through the heater core. When you operate the system manually you'll get 'warm' air out of the vents for a while but it will take the car much longer to reach operating temperature.

 

On the Fusion, there is no heater control valve. Coolant always circulates through the heater core.

 

It is just done so it does not blow cold air on your feet.

[powersb]

2010 Hybrid - Mine usually operates as it is supposed to, by not blowing much until the car warms up, but since it started getting colder, a few times when I start it cold, the blower comes on at high speed, blowing cold air. This has happened 3-4 times this fall/early winter. In fact, it did it to me this morning.

 

Anyone know of a reason this may be happening?

[FFHdriver]

2010 Hybrid - Mine usually operates as it is supposed to, by not blowing much until the car warms up, but since it started getting colder, a few times when I start it cold, the blower comes on at high speed, blowing cold air. This has happened 3-4 times this fall/early winter. In fact, it did it to me this morning.

 

Anyone know of a reason this may be happening?

The system has to get an air sample to determine what the temperature is before adjusting.

[powersb]

The system has to get an air sample to determine what the temperature is before adjusting.

 

 

I don't think that's the case when it happens to me. If it acts up and and the fan goes to high speed right when I start the car, it stays that way until the car interior finally gets close the the set temp then starts ramping down.

[Bob B.]

Hi MTL. :D Yes, this is normal. System is designed not to begin blower operation until the engine has reached an operating temperature where it can circulate warm air at the set/desired temperature.

 

Good luck. :beerchug:

 

My automatic Temp control works as bbf2530 indicates. My set points are in increments of one degree from 65 degrees up. But an increment of 5 degrees from 60 to 65. Is this 5 degree 'jump' normal?. It seems that sometimes I 'need' a set point between 60 & 65 degrees.

[akirby]

My automatic Temp control works as bbf2530 indicates. My set points are in increments of one degree from 65 degrees up. But an increment of 5 degrees from 60 to 65. Is this 5 degree 'jump' normal?. It seems that sometimes I 'need' a set point between 60 & 65 degrees.

 

65 is the lowest automatic temp you can set. When it goes to 60 that's Max A/C mode.