Compressor engaging with Heat?

[-DVP-]

When my A/C is on I can feel the drag from the compressor. Makes sense.

When I use my heat I can feel the same drag as if it is engaging.

This does not make sense to me. Why would my A/C compressor need to run for heat?

Set at 90*, so it isnt blending. I dont understand. Is there a reason for this?

What could cause this?

 

[kikkinasphalt]

its supposed to.

i believe it dehumidifies the air.

 

[hawkeye18]

yeah, which I feel is crap. FWIW, the compressor won't turn on if the ambient air temp sensor says it's below 55 degrees. At least that's how it's supposed to work...

 

[-DVP-]

its supposed to.

i believe it dehumidifies the air.

Well so much for mpg

 

[bigblock]

unless the eact is on vent or floor the compressor will turn on. that's what Ive noticed. its just the way ford programed it i guess.

 

[frosho]

I was wondering about this myself. Somebody should figure out how to change that "feature"... *cough* Hawkeye *cough*

 

[hawkeye18]

what, keep the compressor from turning on? Well the easy way is to unplug the A/C clutch cycling switch on top of the dryer. Or, rig it up so an upside down can of canned air is squirting on your ambient temp sensor at all times... it'll say it's -38 degrees out but at least the compressor won't turn on.

 

[kikkinasphalt]

Well so much for mpg

I was wondering about this myself. Somebody should figure out how to change that "feature"... *cough* Hawkeye *cough*

see below.

what, keep the compressor from turning on? Well the easy way is to unplug the A/C clutch cycling switch on top of the dryer. Or, rig it up so an upside down can of canned air is squirting on your ambient temp sensor at all times... it'll say it's -38 degrees out but at least the compressor won't turn on.

This

 

[frosho]

Then it wouldn't work at all, correct? I was talking about finding a way for it to only comes on with defrost or a/c, not when the heat is on.

 

[hawkeye18]

Then it wouldn't work at all, correct? I was talking about finding a way for it to only comes on with defrost or a/c, not when the heat is on.

that would be difficult to impossible to do without cracking the logic of the EATC itself. You'd have to code extra logic into the unit to discriminate whether it's heating or cooling based on the ambient temp. I suppose if you hooked the blend door wiper arm return wire up to a logic board that measured resistance and activated an NC relay hooked up to the clutch field coil circuit based on what position the blend door was in, you could do that... but man, what a lot of work.

You could also simply wire a switch to the field coil circuit; simply flip the switch off if you don't want the compressor running.

 

[VortecGT]

just unplug it, it will not run if there is no or low refrigerant in it also.

 

[-DVP-]

FWIW, the compressor won't turn on if the ambient air temp sensor says it's below 55 degrees. At least that's how it's supposed to work...

Is this true? If this is the case then I can deal with it until then. I dont use the heat that much until its really cold out.

 

[hawkeye18]

Hopefully this explains a little about AC operation. Ripped from the manual:

 

[bigblock]

that's strange because my compressor kicks in even when the temp is below 50, like today. maybe something is wrong with my ambient air temp sensor? and im sure it doesn't come on when floor is on.

 

[frosho]

that's strange because my compressor kicks in even when the temp is below 50, like today. maybe something is wrong with my ambient air temp sensor? and im sure it doesn't come on when floor is on.

Same here. I'll have to check again to be sure, but I think the clutch is engaging with everything but the Floor setting.

 

[frosho]

that would be difficult to impossible to do without cracking the logic of the EATC itself. You'd have to code extra logic into the unit to discriminate whether it's heating or cooling based on the ambient temp. I suppose if you hooked the blend door wiper arm return wire up to a logic board that measured resistance and activated an NC relay hooked up to the clutch field coil circuit based on what position the blend door was in, you could do that... but man, what a lot of work.

You could also simply wire a switch to the field coil circuit; simply flip the switch off if you don't want the compressor running.

Might as well be speaking Russian to me.

I was only kidding anyway. I figured it would be about as tough or tougher than getting the display to read "SHO."

 

[RonPorter]

You WANT the compressor to run to dehumidify the air when you run Defrost in cold weather.

Leave it alone.

I guess you guys aren't old enough to have driven cars without the feature. The windows (and especially the windshield) would NOT clear on the inside in cold, humid weather.

Plus, a/c compressors would die sooner since they wouldn't be run in winter to keep the unit and seals lubed.

If you want mpg, sell the SHO and buy a **** Prius.

 

[frosho]

You WANT the compressor to run to dehumidify the air when you run Defrost in cold weather.

Leave it alone.

I guess you guys aren't old enough to have driven cars without the feature. The windows (and especially the windshield) would NOT clear on the inside in cold, humid weather.

Plus, a/c compressors would die sooner since they wouldn't be run in winter to keep the unit and seals lubed.

If you want mpg, sell the SHO and buy a **** Prius.

I know that I want the a/c cycling for the defrost settings. But when I'm just trying to warm up my feet and hands with the vent/floor settings, the bogging gets annoying. I hadn't though about the life of the compressor and seals, though. Good point.

I know all about foggy windshields too, the a/c lines in my green POS were rusted out long before I got the car...

 

[sdpatt]

As stated by BigBlock, The VENT and FLOOR settings (in addition to OFF) are the only selections that do not activate the compressor. You can heat the car's interior just fine with both of these settings.

 

[RonPorter]

I know that I want the a/c cycling for the defrost settings. But when I'm just trying to warm up my feet and hands with the vent/floor settings, the bogging gets annoying. I hadn't though about the life of the compressor and seals, though. Good point.

I know all about foggy windshields too, the a/c lines in my green POS were rusted out long before I got the car...

If you are feeling bogging with the compressor on, you have other issues. Either the compressor is going out, or the engine has an issue.

In my SHOs, LGT, or the truck, I can hear the a/c clutch engage, but it does not affect the engine.