Another ac question

[scwill]

Just need an idea of whats going on here. So when i turn on ac it keeps temp, but it will cycle low and high on different settings. Right now its on 73 and i have it on medium and it will blow hard for awhile then blow not as hard. Hope its not major. Anyone had this?

 

[Bardiya]

Probably the fan motor or resistor

 

[Mike6158]

That's how mine works. If it's hot out it slowly brings the speed up when I start the LC and then ramps up to high. I an increase the temp setting and at some setpoint the fan will slow down. Then as the air temp warms up the fan starts to speed up.

 

[Spike555]

The HVAC fan is going to vary it's speed as needed to keep the cabin as close to your set temp as possible, assuming you are using the "AUTO" function.
I set my front and rear at 72 forgot about it. Summer and winter. Let it do it's thing. One less thing I need to think about.

 

[scwill]

So yall are saying its normal? Blows ice cold just small changes in speed. What is the purpose of the auto button? Should i leave it on auto? Thanks

 

[flintknapper]

So yall are saying its normal? Blows ice cold just small changes in speed. What is the purpose of the auto button? Should i leave it on auto? Thanks

Auto function 'maintains' (or tries to maintain) a certain temperature threshold. Say you are most comfortable at 72°F.

You set the temperature at 72°, employ the 'Auto' function and the system will run (as needed) to reach and maintain that temperature.

When you do not use the 'auto' function...then the temperature is 'user/manually' adjusted (I.E. turn the fan speed down and temperature up if you are getting too cold, or the opposite if you are too hot). The 'Auto' feature lets you dispense with that duty and will try to reach and KEEP a selected temperature for you.

So depending upon conditions (vehicle speed, ambient temp, solar gain, etc...) the system will naturally vary the fan speed and compressor engagement.

 

[scwill]

Auto function 'maintains' (or tries to maintain) a certain temperature threshold. Say you are most comfortable at 72°F.

You set the temperature at 72°, employ the 'Auto' function and the system will run (as needed) to reach and maintain that temperature.

When you do not use the 'auto' function...then the temperature is 'user/manually' adjusted (I.E. turn the fan speed down and temperature up if you are getting too cold, or the opposite if you are too hot). The 'Auto' feature lets you dispense with that duty and will try to reach and KEEP a selected temperature for you.

So depending upon conditions (vehicle speed, ambient temp, solar gain, etc...) the system will naturally vary the fan speed and compressor engagement.

So what i described is happing is normal correct?

 

[BullElk]

It is normal IF you have selected the AUTO button.

 

[scwill]

It is normal IF you have selected the AUTO button.

Do most people run that auto button? I had a guy tell me to run the rear ac with the front ac, i guess to not put too much stess on the front.

 

[Spike555]

Do most people run that auto button? I had a guy tell me to run the rear ac with the front ac, i guess to not put too much stess on the front.

There is only one a/c compressor, but there are two evaporator, front and rear. There are also two HVAC (heating ventilation air conditioning) fans, front and rear. There are also two seperate HVAC controls, front and rear. If you set them both to AUTO, they will do just like Flint said, front and rear fans will adjust their speed, temp sensor will add/decrease heat as needed, each intedenpant of one another.
The a/c compressor is going to run as long as the a/c is on no matter what you do.
There is no added strain on anything, the a/c compressor only knows on or off.

If you turn the front HVAC off the rear will still operate. Turn the rear off and the front will still operate.
It's like the a/c in your house, you set the temp on the thermostat and it does the rest, same thing on your truck.
I leave mine set on AUTO, both front and rear, all the time, winter, summer, doesnt matter. Let it do it's thing.
The only time I change it is if the windshield is covered in ice and needs to be cleared, then I put it in defrost. Built go back to AUTO once the windshield is cleared.

 

[scwill]

There is only one a/c compressor, but there are two evaporator, front and rear. There are also two HVAC (heating ventilation air conditioning) fans, front and rear. There are also two seperate HVAC controls, front and rear. If you set them both to AUTO, they will do just like Flint said, front and rear fans will adjust their speed, temp sensor will add/decrease heat as needed, each intedenpant of one another.
The a/c compressor is going to run as long as the a/c is on no matter what you do.
There is no added strain on anything, the a/c compressor only knows on or off.

If you turn the front HVAC off the rear will still operate. Turn the rear off and the front will still operate.
It's like the a/c in your house, you set the temp on the thermostat and it does the rest, same thing on your truck.
I leave mine set on AUTO, both front and rear, all the time, winter, summer, doesnt matter. Let it do it's thing.
The only time I change it is if the windshield is covered in ice and needs to be cleared, then I put it in defrost. Built go back to AUTO once the windshield is cleared.

Right on. Auto it is. Never had a truck with front and rear ac. Appreciate the insight.

 

[Spike555]

Right on. Auto it is. Never had a truck with front and rear ac. Appreciate the insight.

You're welcome.

 

[BullElk]

I personally never use the AUTO option because if the car is 90 degrees and you want to cool it down to 70, the high speed fans are going to run and I don't want the noise of high speed fans nor the wind speed it creates. So I just put it on 70 and med fan. Been working fine for many moons now.

 

[Bardiya]

Probably the fan motor or resistor

Ignore this, I just assumed you had manual HVAC controls

 

[craaaazzy]

i've experienced the same thing as the OP. if i set it to 72 and manually put fans speed to medium (no auto selected), the fan will adjust itself (lower speed) when that temp is reached. i've tested this by manually making it cooler (dropping the temp down to 71) and the fan will blow at medium speed again and once that temp is reached, back itself down. i don't run auto for the same reason bullelk mentioned above, i don't like fan to go on high cause of the sound.

 

[scwill]

There are 2 buttons to the far right on the ac controls. One I believe is to recirculate the air and the other one blows/sucks the air out the back of the truck(in order to keep the cabin a constant temp, I guess when parked?). I think I had it on the exhaust one the other day, at 73, on medium, when the ac was changing power on me. I dont have my truck right now but when I get it back I will keep it on the recirculate button, on 70, on medium, and see what happens. Maybe my ac crapping out, my LC is starting to be more of a pain in the butt then I thought it was going to be.