Calling on AC experts
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Logistics Pro
Joined: May 2004
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Calling on AC experts
I am not overly savvy on AC systems, aside form R&R'ing components and recharging them (home style).
For those that might know:
How does the 2004 F250 system regulate temperature within the cab on Max and regular settings and tells the compressor to cycle on/off?
I read a bit and apparently the orifice tube filter/valve is what cycles the compressor on/off during use and others wrote high/low pressure valves regulate temp by pressure variances, but it was not clear.
My truck is older and I do not have any fancy auto climate stuff just for reference.
I will also add I rebuilt the entire system last year and recently was in 112* heat pulling my boat. I was experiencing a weird fluctuation in temperature and to be honest I was floored. The system had been working flawless and was colder than stock after I was done. I got home yesterday and have not put gauges on it to check pressures. Mid trip back it started blowing cold again
I was ready to put my fist through the dash after looking at my poor family sweating their a$$es off for an hour
Thank you for your time.
For those that might know:
How does the 2004 F250 system regulate temperature within the cab on Max and regular settings and tells the compressor to cycle on/off?
I read a bit and apparently the orifice tube filter/valve is what cycles the compressor on/off during use and others wrote high/low pressure valves regulate temp by pressure variances, but it was not clear.
My truck is older and I do not have any fancy auto climate stuff just for reference.
I will also add I rebuilt the entire system last year and recently was in 112* heat pulling my boat. I was experiencing a weird fluctuation in temperature and to be honest I was floored. The system had been working flawless and was colder than stock after I was done. I got home yesterday and have not put gauges on it to check pressures. Mid trip back it started blowing cold again
I was ready to put my fist through the dash after looking at my poor family sweating their a$$es off for an hour
Thank you for your time.
Hotshot
Joined: Apr 2010
Posts: 19,074
Likes: 247
From: Saratoga Springs,UT
My understanding is It shouldn’t cycle unless you have digital HVAC Control in your dash unit
Cycling on manual climate control is usually high or low pressure out of range or possible wire or clutch issue
im not much help here my compressor locked up on mine so Im researching it too
Cycling on manual climate control is usually high or low pressure out of range or possible wire or clutch issue
im not much help here my compressor locked up on mine so Im researching it too
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Logistics Pro
Joined: May 2004
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Thank you both. I ran it on high idle this morning and the compressor never cycled once and it was blowing just like it was prior to the debacle.
Next in order I am going to change the pigtails on the high and low switches just because they're original and I will put gauges on it.
This blew my mind to be honest, and was in a tail spin over it. Nothing like 110+ weather, you just arrived at the location for a vaca and it starts like this.
Next in order I am going to change the pigtails on the high and low switches just because they're original and I will put gauges on it.
This blew my mind to be honest, and was in a tail spin over it. Nothing like 110+ weather, you just arrived at the location for a vaca and it starts like this.
Fleet Mechanic
Joined: Sep 2006
Posts: 1,491
Likes: 295
From: Fresno, CA
It has a pressure switch on the low side, it will cycle the comrpessor is the pressure gets too low to keep the Evaporator from icing. That usually only happens at light loads, mine is typically running all the time when it's hot.
I'm wondering if your compressor clutch isn't holding all the time? Have you checked the clutch gap?
I'm wondering if your compressor clutch isn't holding all the time? Have you checked the clutch gap?
Hotshot
Joined: Dec 2014
Posts: 17,838
Likes: 3,143
From: Jersey Shore
It could be that one of the pressure switches got stuck, or the contacts within are a little iffy and did not re-engage. Under that high temperature, I would guess it was the high-pressure switch.
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Logistics Pro
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It has a pressure switch on the low side, it will cycle the comrpessor is the pressure gets too low to keep the Evaporator from icing. That usually only happens at light loads, mine is typically running all the time when it's hot.
I'm wondering if your compressor clutch isn't holding all the time? Have you checked the clutch gap?
I'm wondering if your compressor clutch isn't holding all the time? Have you checked the clutch gap?
Every facet of the system is brand new and swapped by me with OEM equipment. I have heard of the clutch gap but again it worked flawless for a year (under normal circumstances) and I never thought twice.
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Logistics Pro
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Jack,
I am still in the infancy stages of diagnosis and info gathering. I tend to think a component is failing because the system is full and brand new from evaporator to compressor and everything in between. Scratching my head on this one.
I'll report with pressures most likely tomorrrow
Thank you again to all
I am still in the infancy stages of diagnosis and info gathering. I tend to think a component is failing because the system is full and brand new from evaporator to compressor and everything in between. Scratching my head on this one.
I'll report with pressures most likely tomorrrow
Thank you again to all
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Joined: Nov 2009
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From: Kansas
Doubt there's much you can do until it happens again other than check connections. If it happens again stop and see if low side is cold. If so is it iced? If not likely a blend door issue. If iced the low side cutout is sticking on This switch could also stick off causing compressor not to run If both lines are warm. If compressor is running and both lines are warm then you have bigger problems.
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Logistics Pro
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Not yet I am at work unexpectedly and won't be home for a few days. I did have a chance to check the temp output on high idle, engine up to temp, center vent on MAX output. The lowest temp I get from the vent is 42.4*F at 93* ambient temp.
The system is working great when it wants to.
I did have a question about checking the pressures. My gauges have the pigtails with the shutoffs and the main gauge manifold has the two valves. I have used them but only under circumstances when I know the system will be evacuated for repair/diagnosis purposes. There is a small loss of R134 from the hoses after diagnosis pressure checks.
My question (and memory refresh):
Only the two valves on the high and low pressure ports are opened and NOT the two main gauge valves when checking system pressure for diagnosis...this sound correct?
How do I recirculate the R134 that is now in the lines back into the system for minimal freon loss?
The loss is a few ounces from what I read and I don't want that to occur.
Thank you
Joe
The system is working great when it wants to.
I did have a question about checking the pressures. My gauges have the pigtails with the shutoffs and the main gauge manifold has the two valves. I have used them but only under circumstances when I know the system will be evacuated for repair/diagnosis purposes. There is a small loss of R134 from the hoses after diagnosis pressure checks.
My question (and memory refresh):
Only the two valves on the high and low pressure ports are opened and NOT the two main gauge valves when checking system pressure for diagnosis...this sound correct?
How do I recirculate the R134 that is now in the lines back into the system for minimal freon loss?
The loss is a few ounces from what I read and I don't want that to occur.
Thank you
Joe
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Logistics Pro
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So I am going to contradict myself. Once I started looking at the system to find part numbers for the high/low switches IT HIT ME. I never replaced the low pressure switch because the day I received the new switch, it was wrong and I needed to charge the system.
I reinstalled the old low pressure switch because I could not find one with my VIN or local dealer was perplexed.
I read the old number off the current switch plus using Jack's valuable info he always passes on to people and confirmed the number is 95BW-19E561-AA.
I ordered the pigtail for that switch, plus an OEM low pressure switch.
I have been digging deep. The blend door is working fine but I ordered the actuator just to try it and it is pretty cheap. The vacuum system is leak free and I am going to zip tie the heater valve shut through the summer....just to make sure.
One dumb question. Does the low pressure switch have a schrader valve so the system does not require to be evacuated?
I recall one of the switches is schradered but I cannot recall which one.
thanks
Joe
I reinstalled the old low pressure switch because I could not find one with my VIN or local dealer was perplexed.
I read the old number off the current switch plus using Jack's valuable info he always passes on to people and confirmed the number is 95BW-19E561-AA.
I ordered the pigtail for that switch, plus an OEM low pressure switch.
I have been digging deep. The blend door is working fine but I ordered the actuator just to try it and it is pretty cheap. The vacuum system is leak free and I am going to zip tie the heater valve shut through the summer....just to make sure.
One dumb question. Does the low pressure switch have a schrader valve so the system does not require to be evacuated?
I recall one of the switches is schradered but I cannot recall which one.
thanks
Joe