Looking for some help troubleshooting a strange A/C compressor issue.

Vehicle: 2006 Ford Escape; 2.3L 4 cyl. Hybrid

My 2006 Escape Hybrid's A/C compressor is engaged regardless of whether or not the A/C is turned on. With the engine off, the A/C clutch turns freely, so it isn't frozen. When starting the vehicle, the compressor is disengaged and then engages 5-6 seconds after starting, again regardless of whether the A/C is in the ON or OFF position. I know the compressor is supposed to come on if the defroster is turned on, but I turned the climate controls to OFF and the compressor stays engaged. ???

Could a low refrigerant charge cause this? Worn out compressor? The system is only registering 22 psi on the low side (engine on, compressor engaged). I don't have a manifold set, just the low side gauge from the A/C Pro refrigerant. I added one can of the A/C Pro refrigerant for hybrids {Who knew hybrids had different refrigerant!!!}, but didn't see any real change. Not sure what to do to troubleshoot further. I can't find anything about this issue on the web.

Any help in troubleshooting would be appreciated. Thanks in advance, you guys always provide invaluable advice!

Can anyone answer the question why hybrids have a different refrigerant than non-hybrids? I heard it was different oil for the compressor. Is the compressor on a hybrid different than a non-hybrid?

Dave
2006 Ford Escape
VIN: 1FMCU96HX6KC06468
2.3L 4 cyl. Hybrid
All Wheel Drive

 

They don't. Your Escape hybrid uses exactly the same stuff as any other Ford of that era. If the can was marked for hybrids, it was some marketing gimmick.

Quick check: Disconnect the low pressure cycling switch while the system is running. Does the clutch disengage?

 

Yes, when I disconnect the low pressure switch the clutch disengages.

 

I wonder if Ford is using the A/C system to cool the electrical components. This could explain the constant on compressor.
Might check with a dealer service to determine if this is normal.
Mike

 

Yep. The control module for the high voltage battery system can activate the A/C (to cool the batteries) regardless of the setting of the passenger compartment climate controls.

 

That explains why the A/C clutch is engaged all the time. I guess it will disengage when the batteries are cool. I'll keep a watch for it.

Now to figure out why the A/C isn't blowing cold air. Seems like everything is running as it should, but the air coming out of the vents is pretty much ambient temperature.

Where do I go from here? Should I add a can of A/C Pro with UV dye (and sealant?) and see if that makes a difference? Are they all the same or are some better than others?

 

You should put gauges on the system to see if the compressor is actually doing anything. I assume it is because a) it's not short-cycling and b) your batteries haven't exploded. If you can locate the refrigerant lines that go to the battery compartment's evaporator, check them to see if they are cold or not.

On the hybrid system, there's a refrigerant valve that has to open to supply refrigerant flow to the passenger compartment evaporator. If the refrigeration system is actually working for the batteries, then I'd be focused on the operation of that valve.

 

Thanks for that insight.

The Haynes manual doesn't give hybrid specific information, so I'll see if I can find the lines. Shouldn't be too hard since I know where they start and where they end (roughly).

 

I followed the refrigerant lines to the battery compartment at rear of the vehicle. They are cold with condensation dripping of them (just the one); so much so that the line was frosted for about 5 inches going into the battery compartment (pic below).


Frosted line going into battery compartment

The line going into the cabin evaporator is coldish; a little condensation, but not much and not nearly as cold as the line going into the battery compartment. In fact its only coldish really close to the evaporator (within 5 or 6 inches or so.)


Valve that controls refrigerant flow to the cabin evap.? I think?

I will investigate the valve in the high pressure line (circled in pic above) leading to the cabin evaporator. It doesn't show up in the Haynes wiring diagram for the A/C system. It looks like a switched ground, but I'm not sure. I think getting a power probe is in order when I pick up the gauge set.

 

I'd bet that your charge is probably still wrong. Gauges time.

You don't need a power probe or to mess with the valve. If it was not opening at all, the line towards the evaporator wouldn't be cold. Actually, none of the lines in that half of the system would be cold as no refrigerant would be flowing through it.

Check the outlet tube of the passenger side compartment. If it isn't cold, then there's not enough refrigerant going through it. The inlet hose should indeed be coldest at the evaporator inlet. The orifice tube is in the line between the valve and the springlock coupling at the evaporator inlet.

 

Did you mean "check the orifice tube of the passenger side ..." or are you talking about the cabin evaporator outlet?

The high pressure line running from the valve to the cabin evaporator gets cold right after the little dimples in the line. I believe that's where the orifice tube is. If so, its cold between the orifice tube and the evaporator. The evaporator outlet line (from the evaporator to the accumulator) is not cold. See pic below.


Blue arrow is area of the orifice tube (can't see it in pic)
Red arrow is leading to accumulator
Blue outlined line is cold (between orifice tube and evaporator)

 

Yeah, that was worded poorly. I meant the "passenger side of the system", dividing the system into passenger & battery compartment subsystems.

All of your symptoms, with the additional details, indicates an undercharged system. When there is sufficient refrigerant flowing through the system, that evaporator outlet should also be cold while the system is running. You can use this a as a poor-man's indicator of when there's enough refrigerant in the system to get you in the ballpark

Since it can be surmised that the previous charge leaked out, it would be worthwhile to find and repair the leak before doing much else since anything you put in now is likely to simply leak out again.

Factory service manual fo the hybrid says the system capacity (from empty) is 41 oz. There's probably a sticker under the hood that either matches this or supersedes the manual.

BTW, Walmart sells R134a in 12 oz cans for $5, use your own gauges or fill adapter. A cheap adapter is about $15 with a single low-side gauge. Check with your local Autozone or O'Reilly's to see if they have manifold gauge sets and/or leak detection kits in their "loaner" programs.

 

The oil is the difference but only if the hybrid utilizes an electric motor to run AC instead of a belt driven compressor. The reason is parts of the electric motors are exposed to the oil and certain oils conduct electricity. These oils can allow a short to ground within the motor and cause problems.

I can’t recall at the moment which oils are unsafe for those systems but even small amounts of contamination can cause problems.

 

Yeah, I did some additional research and did find that same information.

It would appear that, in the factory service manuals, Ford changed the specification for the oil around the 2010 model year for the Escape hybrid from YN-12D to the YN-32 (Electric compressor oil). The current chart at FCSD shows that YN-32 is spec'd for the hybrid going back to the '07 MY, the earliest column on the chart. May have been a TSB or other service message sent out chat changed the specification for older vehciles but I haven't come across it.