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  1. #1
    Join Date
    Sep 2003
    Posts
    16

    Question '98 Air conditioning cuts out

    Sorry, this somehow got posted for the wrong year... My 98 V70 AC works fine and puts out cold air when you first start up. After a while it cuts out and actually starts pumping HOT air into the cabin. (I'm thinking this happens at about the time the engine comes up to temp.) Sometimes you can shut it off for a while and get it to work again for a few minutes but not reliably. The dealership said we needed a new compressor @ $1800. Obviously the compressor works because it delivers cold air, but they said there's another part that is integral with it that failed. Does anyone have any idea what that is and if this is for real? Could it have anything to do with a thermostat? Thanks for everyones help.

  2. #2
    Join Date
    Apr 2003
    Location
    Devon PA
    Posts
    11,409

    Default

    Compressor clutch gap
    The clutch is old, not holding and failing
    You can shim it and it may last for years

    Go to matthews for the el cheapo fix
    www.matthewsvolvosite.com

  3. #3
    Join Date
    Jan 2011
    Location
    Fort Worth Texas or thereabouts
    Posts
    400

    Default

    Dealers usually replace compressor as that fixes the gap and is a warranty backed repair due to the new part.
    If it is the clutch gap you can test for it pretty easily. Run car until the a/c quits. Manually selecting low fan speed will assure it happens quicker (compressor cycles on off more on lower fan).
    Use a yard stick or a 3 foot wooden dowel and tap the non-turning part on front of compressor. Make sure you touch the part towards front of car as it turns CW and that part will turn away from you and have no risk of throwing the yardstick or dowel at you.
    The compressor is down low and forward of engine.
    If the clutch starts and it cools then it is the clutch gap.
    If not there is another item on compressor that can cause the same exact symptoms on hot days: the thermal protection switch.
    This switch cuts off compressor if the back end of compressor gets above a certain temp. Slightly low charge makes this switch cut out compressor but some do it when the switch is active when the right amount of charge is in system. The usual fix is to by pass the switch and connect clutch to incoming power wire directly.

  4. #4
    Join Date
    Sep 2003
    Posts
    16

    Default Question

    Thanks for the information. Do you know if there are fault codes for the thermal protection switch? The dealership told me that a part on the compressor failed that couldn't be replaced separately. Frustrating thing about it is that it works fine when we don't really need the AC. I'd park the car until the weather cools down but I'm concerned about whether the defroster will work in the winter. Any thoughts on that?

  5. #5
    Join Date
    Mar 2009
    Location
    Stonington, CT
    Posts
    111

    Default

    You say you go from having cold A/C air to HOT air? My 98 XC does this once in a while, and it's not a problem with the A/C compressor or clutch, it seems the temperature selector for the passenger side goes flaky and the climate control starts pumping out heated air in attempt to raise the cabin air temp. Cycling the selector knob a few times and returning it to full cold brings back the cold air. The same thing will happen on a normally running system, if you quickly raise the temperature setting of the control, the system cranks in heated air ducted from the heater core to quickly bring the cabin temp up.

    If you really have an intermittent loss of A/C cooling due to a clutch or other compressor control problem the air from the dash vents would stop being cold, and would just gradually go to a warmer temp similar to the outside air temp, but should not go to a hot condition.

    I chased an intermittent loss of A/C on our Ford Escort last summer to a bad piece of wiring between the compressor clutch control relay and the clutch coil on the compressor. Apparently its a fairly common failure mode on those cars. Cost of materials to repair - less than a dollar.

  6. #6
    Join Date
    Sep 2003
    Posts
    16

    Default

    The control issue makes sense. With the weather we've experienced this summer, it really is unbearable when this happens because you can't just run the fan without the AC to get some relief. It blows air that's hotter than ambient.
    Does anyone know if fault codes show up for the thermal protection switch? Somehow the dealership quickly determined it needed a new compressor "because a part attached to the compressor failed" but maybe that was just SOP. Hopefully my foreign car indy guy is a good detective.

  7. #7
    Join Date
    Sep 2003
    Posts
    16

    Question

    Thanks for all the suggestions. The clearance was 1.1mm so we shimmed it with zip ties. So far it's been working fine. That fix was considerably cheaper than the $1800 that the dealership wanted! I just talked to an owner of a '99 (parked near my '98) who has been going without AC all summer. I suggested this site. Question for everyone out there... do they all fail like this? How many miles were on yours when it failed? Mine had 113k.

  8. #8
    Join Date
    Mar 2009
    Location
    Stonington, CT
    Posts
    111

    Default

    Quote Originally Posted by tornrock View Post
    Thanks for all the suggestions. The clearance was 1.1mm so we shimmed it with zip ties. So far it's been working fine.
    Would be interested in hearing more about this fix and if the technique will work on a 94 Escort compressor - the 98XC A/C is fine but I have just trouble shot the same symptoms on the Escort. When hot, the clutch coil is drawing current but not engaging, HFC-134A pressures indicate system charge is OK.

  9. #9
    Join Date
    Jan 2011
    Location
    Fort Worth Texas or thereabouts
    Posts
    400

    Default

    The same issue affects most compressors on most makes. I change clutch gap on Ford trucks and cars, Dodge trucks and cars, and others.

    There is no fault code for the thermal cutout switch on Volvos using it. It interrupts compressor circuit at the final leg of circuit on the compressor.

  10. #10
    Join Date
    Aug 2011
    Location
    NC, USA
    Posts
    11

    Default

    Yes my 2000 XC70 has the same issue. The A/C works fine for a while and then all of a sudden it stops. Luke warm air comes out of the vents. After a few minutes the A/C comes back on. Never sure when it is going to happen it just does.

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