7.3 powerstroke - A/C problem?
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4wd Low
Joined: May 2022
Posts: 11
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7.3 powerstroke - A/C problem?
I guess this problem could be for any truck....mine is a 7.3 diesel.
My A/C starts out blowing pretty cold but then warms up a bit. Never really gets as cold as the first 10 minutes. Mechanic friend noticed that the compressor never disengages/cycles...in other words...A/C compressor clutch is always engaged.
We are thinking the sensor on either the low or high pressure side?
Anyone have any ideas or thoughts on this? Thanks for any suggestions.
My A/C starts out blowing pretty cold but then warms up a bit. Never really gets as cold as the first 10 minutes. Mechanic friend noticed that the compressor never disengages/cycles...in other words...A/C compressor clutch is always engaged.
We are thinking the sensor on either the low or high pressure side?
Anyone have any ideas or thoughts on this? Thanks for any suggestions.
Lead Driver
Joined: Nov 2020
Posts: 7,128
Likes: 1,945
From: Sportsman's Paradise
I guess this problem could be for any truck....mine is a 7.3 diesel.
My A/C starts out blowing pretty cold but then warms up a bit. Never really gets as cold as the first 10 minutes. Mechanic friend noticed that the compressor never disengages/cycles...in other words...A/C compressor clutch is always engaged.
We are thinking the sensor on either the low or high pressure side?
Anyone have any ideas or thoughts on this? Thanks for any suggestions.
My A/C starts out blowing pretty cold but then warms up a bit. Never really gets as cold as the first 10 minutes. Mechanic friend noticed that the compressor never disengages/cycles...in other words...A/C compressor clutch is always engaged.
We are thinking the sensor on either the low or high pressure side?
Anyone have any ideas or thoughts on this? Thanks for any suggestions.
If that is the case, you will want to check the owners manual for the location of the ac relay and pull it to see if the comp cycles off, if it doesn't then you have bigger issues with the comp itself or the clutch.
Really need to put in an experts hands to avoid throwing $$ at it and possibly never fix it.
Thread Starter
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4wd Low
Joined: May 2022
Posts: 11
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I should have clarified....
We had AC gauges hooked up...mechanic says gauges are at correct settings so we believe that the right amount of freon is in the system.
Compressor stays engaged the whole time the AC switch on the dash is turned on........ Blowing cold air but gradually gets warmer......compressor never disengages.
When we disconnected elec connection from either of the 2 AC system sensors (low and high side) the compressor disengages.
So, we are thinking to replace the low side (evaporator.....nearer to the fire wall?) sensor first.
Hope that helps a little bit. Are we on correct path?
We had AC gauges hooked up...mechanic says gauges are at correct settings so we believe that the right amount of freon is in the system.
Compressor stays engaged the whole time the AC switch on the dash is turned on........ Blowing cold air but gradually gets warmer......compressor never disengages.
When we disconnected elec connection from either of the 2 AC system sensors (low and high side) the compressor disengages.
So, we are thinking to replace the low side (evaporator.....nearer to the fire wall?) sensor first.
Hope that helps a little bit. Are we on correct path?
Fleet Owner
Joined: Aug 2010
Posts: 21,253
Likes: 1,656
From: Reynoldsburg, Ohio
I'd monitor the leaving air temperatures from the outlets while in motion at freeway speeds, should see somewhere close or >40* F. I place an old-school stem-type thermometer in the vents looking at them from time to time when driving.
Newer A/C systems in high ambient temperature OR humidity conditions will never achieve maximum efficiency at an idle sitting still.
Newer A/C systems in high ambient temperature OR humidity conditions will never achieve maximum efficiency at an idle sitting still.
i ain't rite
Joined: Mar 2005
Posts: 65,447
Likes: 5,517
From: Marlboro Mental Hospital.
you have to remember, a properly working automotive AC unit is a 20 degree temp differential between inside and outside temps.
so if it is 90 outside, a system putting 65 degrees temp out of the vents is considered properly working.
so if it is 90 outside, a system putting 65 degrees temp out of the vents is considered properly working.
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Lead Driver
Joined: Nov 2020
Posts: 7,128
Likes: 1,945
From: Sportsman's Paradise
I'd monitor the leaving air temperatures from the outlets while in motion at freeway speeds, should see somewhere close or >40* F. I place an old-school stem-type thermometer in the vents looking at them from time to time when driving.
Newer A/C systems in high ambient temperature OR humidity conditions will never achieve maximum efficiency at an idle sitting still.
Newer A/C systems in high ambient temperature OR humidity conditions will never achieve maximum efficiency at an idle sitting still.
This is what my normal reading from the vent is stock. IIRC it was mid 80's that day so that's almost a 45º drop. Idling sitting still. The idling/sitting still theory is a good one for older vehicles with a belt driven fan, almost everything Ford has built since at least 2011 has utilized electric fans.
Now when I manually take over compressor regulation with IDS I can take it down even further.
It might have gotten even colder had I let it run but my nose and ears were beginning to get very uncomfortable so I snapped the pic and jumped out to thaw. brrrrrr. Oh and that's not a blurry pic, that's actual fog blowing out of the vent.
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