RangeRovers.net Forum banner

1 - 10 of 10 Posts

·
Registered
Joined
·
89 Posts
Discussion Starter #1
Hey guys,


I have a weird one. My AC will run nice and strong for several minutes on the highway, and all sudden, it will get warm. Then just as you lose all hope it randomly comes back. All I can think is that the compressor clutch is slipping but I thought I'd put it up to the brain trust and see what you all thought. TIA!
 

·
Registered
Joined
·
89 Posts
Discussion Starter #3
Corroded connector on a sensor somewhere. Check all the HEVAC sensor input readings using Nanocom.
Alas, I don't have a Nanocom or any Rover diagnostic tool. But I do have a multi meter and can always check sensors the old school way! Is there a specific HVAC sensor that you had in mind that might cause this issue?


There is one other clue that might be a coincidence, it seems like when I would accelerate pretty hard, the AC would come back.
 

·
Registered
Joined
·
89 Posts
Discussion Starter #5
improper freon charge maybe, thus causing sensors and switches to cycle until pressures equalize to reactivate clutch.
Possibly but it will run just fine for as long as 15 minutes sometimes. Seems like any issues with the charge would not allow the AC to run that long. I guess it's time to break out the old multi meter and go hunting for issues.
 

·
Registered
Joined
·
434 Posts
what is the air gap on the compressor, minimum clearance is 16 thou about .3mm just slip a feeler gauge in the front of the clutch, the bit that turns freely on the front of compressor , max clearance is .8mm. just undo nut on front and remove shim, washer . i used an oil filter remover to hold clutch . very easy to check and do
 

·
Registered
Joined
·
193 Posts
improper freon charge maybe, thus causing sensors and switches to cycle until pressures equalize to reactivate clutch.
I'd also suggest checking the charge. Could be either too high or too low. Had the same problem on mine for some time. But I had to replace the entire system (less the evaporator which I pressure flushed) as the compressor seized. Called the 'black death'. Once it was charged to the correct weight, it was fine.
 

·
JACK'S GRANDAD
Joined
·
9,197 Posts
Incorrect charge will do it, and would be about my first thing to check.
Are the evaporator fans working ok???
You can back probe them to see if they are getting juice to turn on or not. if they arent turning on, it should cut the ac off to reduce the pressure

Martin
 

·
Registered
Joined
·
22 Posts
My 99 did this. Blend motor for the driver's side flap was goofy. It would run cold then get warm. While on the freeway if I put it in neutral shut the motor off then restarted it, it would flow cold air for awhile then for no reason it would get warm again. It eventually got stuck.
 

·
Registered
Joined
·
513 Posts
Jake,
To answer you earlier question, below is the HEVAC input list. . . . but I agree with others to check how often the compressor is cycling plus the system pressure.

How extreme are the cold-warm cycles ? If it's really quick & wide range then check the blend motor feedback wires for intermittent connections at the HEVAC connections & the feedback potentiometers in the servos. You can unplug them from HEVAC and drive the motors with a 9V battery while reading the potentiometer Ohms on your meter. The reading should be smooth over the full range. If the HEVAC gets no feedback at all it usually goes into "book mode" indicating a fault.

Cannot seem to get attachment upload to work at moment, or I would upload the Nanocom HEVAC PDF. RAVE has all the pin connection details.


  1. VALUES
    • Ambient temperature (c): This reading gives the external air temperature or air entering the ventilation system.
    • Aspirator temperature (c): This reading gives internal cabin temperature.
    • Evaporator temperature (c): This reading gives the evaporator unit's temperature.
    • Heater core temperature (c): This reading gives the engine coolant temperature where
      the coolant enters the heating system.
    • Road speed (Km/h): This value is generated by the ABS ECU using information from its
      wheel rotation sensors.
    • Road speed (mph): This value is generated by the ABS ECU using information from its
      wheel rotation sensors.
    • Engine running:
    • Solar sensor (w/sqm): This reading gives the effective strength of the sun as detected
      by the Solar Sensor mounted beside the Alarm LED on the top of the dashboard.
    • Distribution motors (%): This gives the current feedback position of the motor that
      drives the flap controlling air distribution inside the vehicle. As the distribution buttons are pressed the flap should move to the position which gives air flow to the selected direction (feet, face, screen etc.).
    • Left blend motor (%): This gives the current feedback position of the motor which drives the flap controlling amounts of hot and cold air to be blended together (effectively the temperature of the air coming out of the vents). As the requested temperature is changed by the user the flap should move.
    • Right blend motor (%): This gives the current feedback position of the motor which drives the flap controlling amounts of hot and cold air to be blended together



 
1 - 10 of 10 Posts
Top