climate control vacuum issue
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Elder User
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From: AL
climate control vacuum issue
I have 2004 F250 with manual climate controls. After driving a while I get very little airflow from the dash panel vents. If I select floor, very little air flow. The blower sounds likes it’s blowing against a closed door. I have vacuum under the hood in the reservoir. I can’t find a leak. The strange thing when truck has been sitting all modes work but after driving 45 minutes or so it seems the airflow diverted doors shut. Do I replace the dash selector and/or vacuum actuators under the dash? Has anyone had this problem?
Fleet Owner
Joined: Aug 2010
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From: Reynoldsburg, Ohio
Not sure if your year F-Series is anything close to my "03 E-Series but maybe take a look at a few posts I made about vacuum controls on the heater system: HVAC Vents That might help sort out or diagnose what's causing your problems---I hope its even partially useful.
Hotshot
Joined: Jan 2004
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From: St Louis
There's nothing wrong with your vacuum controls. The system is designed so that there is always an outlet for air that flows through the system (unless there is a foreign blockage in the system).
Probably a frozen evaporator. When it turns into a chunk of ice, air can't flow through it. If the outlet air feels clammy as the airflow fades, that's usually a dead giveaway. Also, if you park it while failed and come back an hour later to a huge poll of water under the truck, that's another giveaway. If so, you likely have an issue with the compressor clutch control.
Check for that condition first. If it doesn't appear to be the case, then there's something in there that doesn't belong. I've seen plastic bags and critter nests cause problems.
Probably a frozen evaporator. When it turns into a chunk of ice, air can't flow through it. If the outlet air feels clammy as the airflow fades, that's usually a dead giveaway. Also, if you park it while failed and come back an hour later to a huge poll of water under the truck, that's another giveaway. If so, you likely have an issue with the compressor clutch control.
Check for that condition first. If it doesn't appear to be the case, then there's something in there that doesn't belong. I've seen plastic bags and critter nests cause problems.
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Elder User
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From: AL
There's nothing wrong with your vacuum controls. The system is designed so that there is always an outlet for air that flows through the system (unless there is a foreign blockage in the system).
Probably a frozen evaporator. When it turns into a chunk of ice, air can't flow through it. If the outlet air feels clammy as the airflow fades, that's usually a dead giveaway. Also, if you park it while failed and come back an hour later to a huge poll of water under the truck, that's another giveaway. If so, you likely have an issue with the compressor clutch control.
Check for that condition first. If it doesn't appear to be the case, then there's something in there that doesn't belong. I've seen plastic bags and critter nests cause problems.
Probably a frozen evaporator. When it turns into a chunk of ice, air can't flow through it. If the outlet air feels clammy as the airflow fades, that's usually a dead giveaway. Also, if you park it while failed and come back an hour later to a huge poll of water under the truck, that's another giveaway. If so, you likely have an issue with the compressor clutch control.
Check for that condition first. If it doesn't appear to be the case, then there's something in there that doesn't belong. I've seen plastic bags and critter nests cause problems.
The evap sound plausible because the condition happens after I’ve driven awhile. It also happens when it’s cold and I run the heater but I do switch between floor and floor defrost to keep the fog off so the evap could still mess up. I‘ll watch for a large pool of water under the evap drain now that it’s warning up. I’ll pull out the shop manual and figure out how to tear into the vent system. Maybe something is in there.
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From: AL
projectSHO89, I think you're on to something. Drove with defrost and floor vent on, thermostat just barely on cold, after 30 minutes no airflow and things got clammy. Stopped for about 15 minutes, got in truck and presto full airflow, nice cold air. I'm realizing now I never hear the compressor clutch engage, I typically hear it, it's slight but I can usually tell when it cycles at red lights. I had the compressor and under hood components replaced a little over a year ago. I'm going to have that shop check it out since they have a lifetime warranty. Thanks for the tip.
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