2006 Ford Fusion Compresoor not engaging

Tiny
BLHOOVER86
  • MEMBER
  • 2006 FORD FUSION
  • 4 CYL
  • FWD
  • MANUAL
  • 80,000 MILES
I have the above car and the AC was working fine. I turned it on the other day and nothing happened. I determined that the compressor is not engaging. I had someone check the system for Freon and the pressure is good. The AC had been cooling great. I checked the fuse in the car and up in the engine compartment. From what I read, it sounds like it could be the Evap temp sensor that is the problem. Is there a way to bypass the relay in the engine compartment to make sure that it's not a compressor or clutch. There are 5 connections on the relay, which 2 do I "jump" to trick the compressor? If it is the temp sensor, is there anyway to replace it without removing the whole dash assy? Any advisce would be appreciated.
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Sunday, May 23rd, 2010 AT 1:17 PM

5 Replies

Tiny
CARADIODOC
  • EXPERT
Hi blhoover86. Welcome to the forum. It's not the temperature sensor. You would have greatly different symptoms if it was out of calibration.

The easiest way to bypass the relay is to pop its cover off, reinstall it, and squeeze the contact. To jump the terminals, (I'm assuming you have standard relays; I don't have a car here to peek at), if you have the normal 1" square relays, there are two terminals on the sides that are parallel to each other. Disregard those. Also disregard the center terminal. That leaves you with two terminals that form the letter "T". Those are the two to connect.

If you have the smaller 1" x 3/4" relays, there will be three terminals on one end that are parallel to each other. Use the middle one of those three and disregard the outer two. Also disregard the one in the middle and use the remaining one on the other end.

Caradiodoc
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Sunday, May 23rd, 2010 AT 2:32 PM
Tiny
BLHOOVER86
  • MEMBER
I have the smaller relays. I took out the relay and tried to jump the ones you suggested (middle one of the three parallel and the one fartherest away). There are not any connectors in the middle of the 3 parallel ones. I quickly tested each one and found that 3 and 4 (the 2 parallel ones) were the ones that would bypass the relay and force the compressor to run. It seemed to run although a little labored. I only left it connected for about 2 minutes to verify the car was starting to cool, which it was. In that short of time, there was a valve or something that seemed to blow to release pressure. I don't know what it was, I only know that it emptied out my radiator overflow tank. It happened somewhere around the shift mechanism on the transmission. I put water back in the overflow, started the car and it ran fine. NO LEAKS. AC compressor still will not run. I wasn't brave enough to try to "jump" it again. Any suggestions? What symptoms would I have if the Evaporator Temperature Sensor was not working? From what I have read, that seems to be a problem with this car. I did notice that my check engine light is on after leaving the battery disconnected for about 20 minutes. Heading off to see someone who has the computer to read the error code. Might shed more light on this. Any input you have will be greatly appreciated.
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Sunday, May 23rd, 2010 AT 3:15 PM
Tiny
CARADIODOC
  • EXPERT
A malfunctioning temperature sensor will affect how much refrigerant is allowed into the evaporator. If too little enters, there will be insufficient cooling. Too much and the evaporator will go below 32 degrees at which point the condensation will freeze and block air flow. You would experience great cooling for a few minutes, then a loss of air flow until the ice melted.

Now, that's how MOST cars work. In yours, they might be using the sensor to cycle the compressor on and off via a computer. Lord knows every former simple, trouble-free system on today's cars has a miserable computer added to it. I'm not aware of any common, or pattern failures with the sensor but that doesn't mean it isn't possible.

Just out of curiosity, have you noticed if the electric radiator fan runs at times? If it does not run in slow traffic after the engine is warmed up, that could be related to the compressor not turning on.

Caradiodoc
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Sunday, May 23rd, 2010 AT 3:28 PM
Tiny
BLHOOVER86
  • MEMBER
Fan works fine. I found out that that is was antifreeze coming out of the overflow when the pressure built up after I jumped the relay. The compressor works. Something, relay or sensor is keeping the compressor from engagine. Are there any relays or fuses or sensors (in the engine compartment) that can be checked. I checked the fuses and relays that were obvious in the owner manual, but I didn't know if there were any that would also keep the AC compressor from not coming on.
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Sunday, May 23rd, 2010 AT 6:52 PM
Tiny
CARADIODOC
  • EXPERT
If the refrigerant charge is low, the low pressure cutout switch will prevent the compressor from turning on. That is done to prevent the low side from getting sucked into a vacuum and potentially drawing in outside air through the leak and bringing in the harmful moisture, (humidity) with it. That switch is somewhere between the condenser in front of the radiator and the expansion valve by the firewall. You can jump that two-wire connector with a piece of wire. If the compressor turns on, the system should be checked for leaks and recharged.

Some systems are no longer using the low pressure cutout switch. Instead, they use a single pressure sensor to monitor system operation. I haven't worked on any of those systems.

Caradiodoc
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Sunday, May 23rd, 2010 AT 7:51 PM

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