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 AC quit after coolant leak

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Sprocket

Sprocket

Posts : 5897
Join date : 2008-11-04
Location : Palm Beach County

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PostSubject: AC quit after coolant leak   AC quit after coolant leak Icon_minitimeThu Aug 12, 2021 5:56 pm

My coolant T blew last night a couple blocks from the house. Fixed it today and now the AC compressor doesn't go on and both fans run as soon as I start the car. Regardless if the AC is on or not. I know they shouldn't run if it's off


AC was working fine when the t blew 2 blocks from the house.....
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silverfox103
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silverfox103

Posts : 3242
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Age : 72
Location : Littleton, NH & St. Simons, GA

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PostSubject: Re: AC quit after coolant leak   AC quit after coolant leak Icon_minitimeThu Aug 12, 2021 6:10 pm

As you know John, with both fans on, something is telling the PCM either the AC is on or temperature is at the high limit, which is not the case>

A guess: sensor on the water pump giving false readings after an overheat?

Tom
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Sprocket

Sprocket

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PostSubject: Re: AC quit after coolant leak   AC quit after coolant leak Icon_minitimeThu Aug 12, 2021 9:10 pm

silverfox103 wrote:
As you know John, with both fans on, something is telling the PCM either the AC is on or temperature is at the high limit, which is not the case>

A guess: sensor on the water pump giving false readings after an overheat?

Tom

no overheat, the T blew within 2 blocks of the house, temp reading was normal when I parked the car. Got out and smelled coolant, looked under and saw a waterfall. Popped hood started it up and coolant was shooting out of the broken T, so I didn't even run it dry.
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booster



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Join date : 2020-04-21
Location : Andover, Minnesota

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PostSubject: Re: AC quit after coolant leak   AC quit after coolant leak Icon_minitimeThu Aug 12, 2021 9:39 pm

Did it hose down the fuse/relay box in at the firewall on the passenger side?
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Sprocket

Sprocket

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PostSubject: Re: AC quit after coolant leak   AC quit after coolant leak Icon_minitimeFri Aug 13, 2021 9:30 am

booster wrote:
Did it hose down the fuse/relay box in at the firewall on the passenger side?

more than likely as the the under hood light lens was full of coolant.

could it have fried the relay? The cover was on the box and it seems dry inside (I did look in there but did not pull the AC relay out).
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jayoldschool

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PostSubject: Re: AC quit after coolant leak   AC quit after coolant leak Icon_minitimeFri Aug 13, 2021 12:12 pm

Unplug the connector on the accumulator. Start car, turn on ac. Use a piece of wire to connect the two terminals on the connector, compressor should start. Once you've confirmed that, you can continue the trouble shooting.
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Sprocket

Sprocket

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PostSubject: Re: AC quit after coolant leak   AC quit after coolant leak Icon_minitimeSat Aug 14, 2021 3:25 pm

jayoldschool wrote:
Unplug the connector on the accumulator.  Start car, turn on ac.  Use a piece of wire to connect the two terminals on the connector, compressor should start.  Once you've confirmed that, you can continue the trouble shooting.

first thing I tried.  didn't help.

What I don't get is why both fans run whether or not the AC is turned off or on. If the AC is off, neither fan should run until I get to 228F. I verified this when the AC was broken. Something else is afoot here....
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jayoldschool

jayoldschool

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PostSubject: Re: AC quit after coolant leak   AC quit after coolant leak Icon_minitimeSat Aug 14, 2021 3:38 pm

Yeah, I figured you've dealt with enough AC to know the pressure switch trick. Bad temp sender on water pump?
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booster



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PostSubject: Re: AC quit after coolant leak   AC quit after coolant leak Icon_minitimeSat Aug 14, 2021 3:53 pm

Sprocket wrote:
jayoldschool wrote:
Unplug the connector on the accumulator.  Start car, turn on ac.  Use a piece of wire to connect the two terminals on the connector, compressor should start.  Once you've confirmed that, you can continue the trouble shooting.

first thing I tried.  didn't help.

What I don't get is why both fans run whether or not the AC is turned off or on.   If the AC is off, neither fan should run until I get to 228F.   I verified this when the AC was broken.  Something else is afoot here....

That was why I questioned about the small box.  On mine, the cover fit poorly and where the cables go in is pretty much unsealed, so it looked like water intrusion would be pretty easy.

You might want to check to see if the relays are getting a single to turn on from the PCM or not, which might give you a clue.

I think both fans come on together if the PCM goes into hot mode so the coolant temp switch shorting that someone mentioned might do that.
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Sprocket

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PostSubject: Re: AC quit after coolant leak   AC quit after coolant leak Icon_minitimeSat Aug 14, 2021 5:47 pm

SOLVED! I got a new ALDL cable to work with my new PC and got it all hooked up. Loaded EE Hack
and saw two trouble codes (Check Engine light was not on).
Something EGR related, and the other said Very low coolant temp (But it was about 90 degrees on the readout). Cleared the codes and the AC Compressor kicked right on.

I had read in the FSM that the PCM shuts down the AC compressor on extreme hot or cold temps.
I had even pulled the battery ground off for 5 minutes and that didn't clear it either.

Well happy to have AC as the AC in our 'new' 210K mile Ford the blend door motor went and stuck on full heat....
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jayoldschool

jayoldschool

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PostSubject: Re: AC quit after coolant leak   AC quit after coolant leak Icon_minitimeSun Aug 15, 2021 4:51 pm

Good stuff. Might want to throw a coolant temp sender in the glovebox. The one on the WP, not the head.
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