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2003 F250 air con blows cold and hot
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flossysez
New User
Feb 19, 2009, 12:16 AM
Post #1 of 5
(6364 views)
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2003 F250 air con blows cold and hot
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2003 ford F250 4.2 litre 6 cylinder 130000 kms
Our air conditioner blows cold air for about 10 min and then hot air. When we turn the air con off for 10 min and then again on the same thing happens.
We have had it re gassed twice and today we had it coneccted to a ford computer and nothing
All presures are acurate and all electronics are fine.
I was hoping that someone has had the same problem and has been able to fix it.
All advice will be appreciated
Cheers Flossy
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Feb 19, 2009, 12:47 AM
Post #2 of 5
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Re: 2003 F250 air con blows cold and hot
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I think this uses a CCOT system = Clutch Cycling Orafice Tube set up. What is probably happening is the compressor continues to operate too long and ices up the evaporator which can't do it's job when iced - actually feels warmer with reduced air flow usually if so.
Look for frost or ice on return (larger) lines from firewall and with a pressure test you may notice the low side pressure is below 26psi and might be the fault of the LPCO (Low Pressure Cut Out) switch.
You may also notice clutch doesn't cycle with this condition.
Guessing at this point but could be just that,
T
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flossysez
New User
Feb 19, 2009, 1:37 PM
Post #3 of 5
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Re: 2003 F250 air con blows cold and hot
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Thanks for the help tom
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flossysez
New User
Feb 19, 2009, 1:41 PM
Post #4 of 5
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Re: 2003 F250 air con blows cold and hot
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Tom, Flossy again, would you have any ide how to correct this problem
cheers Flossy
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Feb 19, 2009, 3:13 PM
Post #5 of 5
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Re: 2003 F250 air con blows cold and hot
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Yes - First we need to determine that compressor is in fact staying on too long for the situation. CCOT systems use a switch the cuts power to the compressor when pressure drops too low which also equates to low temps - looooong story on why that is.
OK: If you can just watch your compressor run - outer head/plate will spin when it's engaged. When it's done it's job - meaning it has overcome the load on it, it should take a break - AKA cycling. On the hottest days at idle it may just stay running and that would be normal.
It would be best if you could watch the pressure if this is what's happening. At roughly 26-7-8 or so PSI the switch should shut off the compressor. If it continued when lower it could frost up the evaporator (inside dash) and that icy mess doesn't throw much cool at you, no normal condensate (water) would be seen dripping under vehicle (might not if real dry air) and might make a flood of water if sitting still when it melts like after you shut the vehicle down AFTER it went warm on you.
#2 there is a typical LPCO (low pressure cut out) switch. The thing is just a pressure switch and just unscrews and a new one just screws on with a shrader to keep refrigerant gas in but you need to go fast and use a heavy glove to swap it. Some may not use a Shrader valve and all refrigerant would come blasting out and that's dangerous and you don't want that. I'm almost certain this will just unscrew with one hiss and that's it but don't blame me if it doesn't!!
You could just unplug this thing and compressor would shut off.
YOU MUST KNOW WHICH SWITCH YOU ARE DEALING WITH. LPCO IS ON THE RETURN SIDE, WOULD BE COLDER TUBING WHEN RUNNING, LARGER DIAMETER HOSE BOTH METAL AND RUBBER AND HEADS TO THE COMPRESSOR. THE HIGH SIDE LEAVES THE COMPRESSOR IN SMALLER DIAMETER TUBING/HOSE, ALSO HAS A CUT OUT FOR OVERPRESSURE ISSUES AND SHOULD NOT BE TOUCHED WITH THIS PROBLEM.
There could be something else causing this and not just a failed switch. You have to do the observing for me, feel temp of return line and look for frost - might not.
This might also just be low of charge of refrigerant and if so DON'T JUST GO ADDING any till you know lot's more info about if in fact it does!!!!
**********
You may notice your A/C stays cool at idle if warm enough out with blower on high and windows open as it can't defeat that much work to make ice. That would be more proof that compressor is working too long for the job when moving along, windows closed, and especially if blower is less that highest request.
Let me know. We should be able to diag this with minimal to no special anythings,
T
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