2001 V70XC - Testing AC function over VIDA

[firstv70volvo]

Thanks again for your diligence.

I was able to measure the clutch gaps close to 12, 3, 9 o'clock positions last night - cold engine; the feeler 0.038 slides in without resistance where 0.040 takes some wiggle. Is this a large gap?

I'll hook up my PITTSBURG Manifold Gauge next for high and low pressure reading -- the gauge came with instructions.

The gap you measured is on the high side, I don't know what the upper spec limit is but I've worked on several AC compressors that have had clutch engagement problems with a clutch airgap smaller than this, around .031 to 0.033 inch.
Because you're only getting cool air from your AC system initially I would suspect a low charge more than a clutch engagement problem. Typically when the airgap gets too large the clutch doesn't engage at all, the coil can't pull in the outside plate so the compressor isn't running and you just get warm/hot air inside the car. With your symptoms, the best thing for you to look at when the air goes from cool to warm is to see if the clutch is still engaged, when you detect warm air in the car check to see if the clutch is engaged, it should be, the inner part of the pulley should be spinning. If the clutch is engaged and the inside air is blowing warm then in this case it's a different problem and gauge readings will help diagnose.

Your comment above (in bold) made me look at my Feeler Gauge again; it is this gauge pictured below... therefore the gap I reported above was a reading error. The correct reading is "I was able to measure the clutch gaps close to 12, 3, 9 o'clock positions last night - cold engine; the feeler 0.38mm (0.015 in) slides in without resistance where 0.40mm (0.0157 in) takes some wiggle."

0.0157 inch is fine, there shouldn't be any problems with clutch engagement with this gap.

[firstv70volvo]

Thanks again for your diligence.

I was able to measure the clutch gaps close to 12, 3, 9 o'clock positions last night - cold engine; the feeler 0.038 slides in without resistance where 0.040 takes some wiggle. Is this a large gap?

I'll hook up my PITTSBURG Manifold Gauge next for high and low pressure reading -- the gauge came with instructions.

The gap you measured is on the high side, I don't know what the upper spec limit is but I've worked on several AC compressors that have had clutch engagement problems with a clutch airgap smaller than this, around .031 to 0.033 inch.
Because you're only getting cool air from your AC system initially I would suspect a low charge more than a clutch engagement problem. Typically when the airgap gets too large the clutch doesn't engage at all, the coil can't pull in the outside plate so the compressor isn't running and you just get warm/hot air inside the car. With your symptoms, the best thing for you to look at when the air goes from cool to warm is to see if the clutch is still engaged, when you detect warm air in the car check to see if the clutch is engaged, it should be, the inner part of the pulley should be spinning. If the clutch is engaged and the inside air is blowing warm then in this case it's a different problem and gauge readings will help diagnose.

Your comment above (in bold) made me look at my Feeler Gauge again; it is this gauge pictured below... therefore the gap I reported above was a reading error. The correct reading is "I was able to measure the clutch gaps close to 12, 3, 9 o'clock positions last night - cold engine; the feeler 0.38mm (0.015 in) slides in without resistance where 0.40mm (0.0157 in) takes some wiggle."

0.0157 inch is fine, there shouldn't be any problems with clutch engagement with this gap.

[xHeart]

The gap you measured is on the high side, I don't know what the upper spec limit is but I've worked on several AC compressors that have had clutch engagement problems with a clutch airgap smaller than this, around .031 to 0.033 inch.
Because you're only getting cool air from your AC system initially I would suspect a low charge more than a clutch engagement problem. Typically when the airgap gets too large the clutch doesn't engage at all, the coil can't pull in the outside plate so the compressor isn't running and you just get warm/hot air inside the car. With your symptoms, the best thing for you to look at when the air goes from cool to warm is to see if the clutch is still engaged, when you detect warm air in the car check to see if the clutch is engaged, it should be, the inner part of the pulley should be spinning. If the clutch is engaged and the inside air is blowing warm then in this case it's a different problem and gauge readings will help diagnose.

Thank you!

Could this procedure include hooking up manifold gauge first and then "look at when the air goes from cool to warm is to see if the clutch is still engaged..."?

Yes, that would be even better to have the gauge pressure readings when the air temp changes. If the air temp changes consistently after about 10 minutes it would be good to monitor the hi/low pressure readings and watch the clutch pulley around the time of any change in air temperature. The gauge pressure readings will confirm if the clutch disengages for any length of time and could also detect if the clutch is slipping or some other problem but I think it's less probable the clutch is slipping.

Here is my progress using Harbor Freight manifold gauge. I used the instruction card that says Dynamic Diagnostic.

Warm engine-running, AC running; opened the coupler valve at HP and LP. I'm reading the dial with blue marking for R134a - with cool air the gauge reads 134@HP and 42@LP (210/38psi) clutch engaged.

Ten minutes later, the clutch disengages with 134@HP and 66@LP, blowing barely cool air. Gradually the gauge changes to 128@HP and 86-90@LP (180/100psi) with warm air and clutch remains disengaged.

[firstv70volvo]

Thank you!

Could this procedure include hooking up manifold gauge first and then "look at when the air goes from cool to warm is to see if the clutch is still engaged..."?

Yes, that would be even better to have the gauge pressure readings when the air temp changes. If the air temp changes consistently after about 10 minutes it would be good to monitor the hi/low pressure readings and watch the clutch pulley around the time of any change in air temperature. The gauge pressure readings will confirm if the clutch disengages for any length of time and could also detect if the clutch is slipping or some other problem but I think it's less probable the clutch is slipping.

Here is my progress using Harbor Freight manifold gauge. I used the instruction card that says Dynamic Diagnostic.

Warm engine-running, AC running; opened the coupler valve at HP and LP. I'm reading the dial with blue marking for R134a - with cool air the gauge reads 134@HP and 42@LP (210/38psi) clutch engaged.

Ten minutes later, the clutch disengages with 134@HP and 66@LP, blowing barely cool air. Gradually the gauge changes to 128@HP and 86-90@LP (180/100psi) with warm air and clutch remains disengaged.

The HP and LP readings when the compressor clutch is engaged look reasonable, possibly slightly low on charge because the low side reading looks a little low. The pressures look high enough not to shut the compressor down due to a very low refrigerant charge. If the clutch isn't disengaging from a very low charge then it's more likely a problem with the air-gap. Once the clutch is disengaged the pressures will begin to equalize and what you're seeing.

Be very careful with the manifold valves, you want them closed all the time unless you're evacuating, vacuuming or recharging the system (low side only). You don't need these valves open to get the pressure readings. These valves connect the low or high side to the center line and can connect the high and low side together if they're both open, something you never one to do when the system is running.

[abscate]

Clutch gap spec 0,3-0,5 mm

[xHeart]

Be very careful with the manifold valves, you want them closed all the time unless you're evacuating, vacuuming or recharging the system (low side only). You don't need these valves open to get the pressure readings. These valves connect the low or high side to the center line and can connect the high and low side together if they're both open, something you never one to do when the system is running.

Helpful.

The fault tracing procedure in VIDA, using the manifold, presents 6 possible scenarios. The unit of measure is (LT) (bar) for low pressure and (HT) (bar) high pressure; which can then be layered over scale/range (like the fuel gauge on dash) to determine the state of AC system and possible next step.

I'm not sure how to read/translate either PSI or R134a markers to (LT) (bar) and (HT) (bar); is HT means high temp, and LT low temp?

I'm using this manifold:

[firstv70volvo]

Be very careful with the manifold valves, you want them closed all the time unless you're evacuating, vacuuming or recharging the system (low side only). You don't need these valves open to get the pressure readings. These valves connect the low or high side to the center line and can connect the high and low side together if they're both open, something you never one to do when the system is running.

Helpful.

The fault tracing procedure in VIDA, using the manifold, presents 6 possible scenarios. The unit of measure is (LT) (bar) for low pressure and (HT) (bar) high pressure; which can then be layered over scale/range (like the fuel gauge on dash) to determine the state of AC system and possible next step.

I'm not sure how to read/translate either PSI or R134a markers to (LT) (bar) and (HT) (bar); is HT means high temp, and LT low temp?

I'm using this manifold:

If the unit of measure in VIDA is bar then you'll have to convert PSI to Bar, which is PSI * 0.0689475729. There are calculators online where you can just plug in the PSI reading and it will convert to bar for you.

When your compressor clutch was engaged you read 210 psi on the high side, which is 14.48 bar and 38 psi on the low side, which is 2.62 bar.

With your compressor clutch disengaging it would be helpful if VIDA can monitor the compressor clutch on/off signal to see if the signal is actually changing to command the disengagement of the clutch at the time of disengagement of if the clutch signal is consistently on and the clutch is just disengaging on its own.