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The Volvo from Hell

marvin-miller on Fri January 11, 2008 8:11 PM User is offline

Year: 1998
Make: Volvo
Model: S70 T5
Engine Size: 2.3
Refrigerant Type: 134a
Ambient Temp: 8c
Pressure Low: Normal
Pressure High: Unknown
Country of Origin: Sweden

Hi Folks;

I've got the Volvo from Hell here and it's really starting to annoy me. It's a '98 S70 T5

The problem is this - the A/C works perfectly in the shop but not on the road.

Clutch cycles fine, it's a new OEM compressor, gap is perfect - system works well (blows about 1.5 c on Max/Max)

Problem: When driving the clutch works but only for a short time. After about 5 minutes compressor stops engaging. If you pull over you can see that it's not working.

Return vehicle to shop - compressor works. Take on test drive - works for about 5 minutes then fails to come back on.

Return to shop and idle - compressor works.

Clutch gap = perfect

Any ideas?

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Best & Thanks;
Marvin

Chick on Fri January 11, 2008 10:32 PM User is offlineView users profile

Filled by weight? Auto temp control? lots of crazy sensors in the system??

Oh, and does it have a diagnostic system built in where you can retrieve codes and sensor operation??

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

Edited: Fri January 11, 2008 at 10:33 PM by Chick

marvin-miller on Fri January 11, 2008 10:39 PM User is offline

Hi Chick!

Evacuated to 750 microns, filled to exact weight (26.4 oz), exact oil level - system spotless & hermetically sealed.

A new compressor was installed (OEM volvo unit from AMA) as well as evap & o-tube.

System is perfect - works like a top when it's in the shop.

Drive it down the road and the compressor stops working.

It does have dual zone auto temp controls. For sensors it has 3 - one on the compressor (HPCO) which is new (came with compressor). Also, the pressure cycling switch is new from AMA. I swapped out the new one for the old one and it's pretty much the same symptoms. There is a third sensor located in one of the lines (liquid line?) - I know not what it does but it does not leak.

I haven't checked for codes - yet....

-------------------------
Best & Thanks;
Marvin

Chick on Fri January 11, 2008 10:47 PM User is offlineView users profile

I try my best to stay away from Volvos at all costs since they did away with high side ports..., but the sensor in the line could be a thermistor, which if acting "flukey" could be shutting the system down. Also the control head itself could be acting up. Best to confirm that the one in the line is a temp/pressure thermistor, I do know that on GM cars, they shut the compressor off when out of whack.. Maybe when Bohica checks this thread he can add to it, as I think he has a "fondness" for the Volvo....

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

marvin-miller on Fri January 11, 2008 10:53 PM User is offline

Quote
I try my best to stay away from Volvos at all costs since they did away with high side ports...

I know - evacuation time was greatly increased by Volvo's brilliant engineering. It would also be nice to know what the high side readings are but the thing is - it's a new OEM compressor and the system blows ice cubes - in the shop....

Quote
but the sensor in the line could be a thermistor, which if acting "flukey" could be shutting the system down. Also the control head itself could be acting up. Best to confirm that the one in the line is a temp/pressure thermistor, I do know that on GM cars, they shut the compressor off when out of whack..

I've been considering that too..... the customer has another identical car so I guess I could start taking them apart and swapping pieces until it works - that's assuming the other car works properly (which is not an assumption I'll be making!). With regards to the 3rd sensor (thermistor/?) - it looks to me like it's a permanent part of the steel line.....

Quote
Maybe when Bohica checks this thread he can add to it, as I think he has a "fondness" for the Volvo....

Say it isn't so! I've always had a deep respect for Brad..... ;-)

Thanks for your input Chick - it's always appreciated even if it just confirms the direction I'm going! :-)

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Best & Thanks;
Marvin

Chick on Fri January 11, 2008 11:01 PM User is offlineView users profile

Just by chance, do you notice orange AC and rec led's flashing for around 20 seconds or so on start up, or during drive? (That would confirm a code) That is a very sophisticated system according to Mitchell.. Good luck with it....

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

marvin-miller on Fri January 11, 2008 11:08 PM User is offline

It can't be any worse them some of the Cadillacs I've had to fix. Tracked that one back to bulging capacitors - yeeeuk!!!

I can't say that that the two lights were flashing on the controller. I also have Mitchell but I was hoping for the majic Volvo bullet - such as - I've had 5 do that and it's always this ;-)

I think what I'm going to do is drive it again tomorrow and while it's acting up I'll tap on the compressor to see if the clutch engages. If so, it's the new oem compressor clutch and that will make Tim very unhappy. If not, I'll borrow buddies scan tool on Monday and take note of any codes and then clear them.

I'm hoping this is a pre-existing condition that did not appear upon initial inspection (I don't test drive during an estimate). It's a good thing I do test drive post-work though because otherwise I would never have caught it. Driving around with a digital thermometer in the dash shows the compressor working and then stopping clear as day.

The only problem is, the ambient up here is 6c and so I have to bundle up and wear a toque on the test drives. There's just something about having the heated seat on while the A/C is on Max/Max that's just wierd! ;-)

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Best & Thanks;
Marvin

Chick on Fri January 11, 2008 11:13 PM User is offlineView users profile

OK, I'm a "Fahrenheit guy" so I just figure it's cold up there... It may be operating properly in that case.. They do cycle when it's cold (condenser cools real fast with cold air coming thru it) ... Very hard to test drive in the cold...Hope this helps..

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

marvin-miller on Fri January 11, 2008 11:18 PM User is offline

Na...it's a CCOT system. It _should_ cut off when the pressure drops in the evap and then re-start when the pressure rises (just like a GM) That's what it does in the shop anyway. I'll borrow his silver one tomorrow and see if it does the same. If so, it's a very poorly written piece of software in the controller. That wouldn't surprise me given the allen key bolts on the suction/discharge fittings on the rear of the compressor or the missing high side fitting or the......

But for the record - 0c is freezing so 6c ambient is pretty cold when you're running with Max/Max a/c. In the shop the vent temps drop to 1.6c before the cycling switch cuts out :-)

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Best & Thanks;
Marvin

bohica2xo on Sat January 12, 2008 2:47 AM User is offline

Marvin:

I do have a soft spot for older SAAB's, and learned my way around Vo-Vo's in self defense. Once Genital Motors put their fingers into SAAB they became just an overpriced Saturn. "Brick" Volvos are good cars, but just as quirky as the SAAB. What you have is an ugly ford made piecemeal in several countries...


To answer the question at hand, the outside temperature sensor is biting you in the backside. Take a look at where the damn thing is, and you will get the picture. As the car idles in the shop, the sensor gets enough heat to allow A/C operation. When you road test, the air pulls it down far enough to drop the A/C out. The difference in ohms around that point is small compared to the sensor total range - a bit of connector resistance can make things worse as well...

You might try blocking the grille or most of the radiator for road testing below 20c ambients.



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"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

Edited: Sat January 12, 2008 at 2:48 AM by bohica2xo

marvin-miller on Sat January 12, 2008 5:43 AM User is offline

Thaqnks Brad - that makes sense. It works fine for the first few minutes on the road but as soon as the speed increases - out it goes. Pull over for a bit and all of a sudden it comes back on. Drive it, and it works for the first few minutes. Etc. Unfortunately, a pre-existing condition like this did not show up on the original diagnosis/estimate as I don't test drive estimates. I thought I was going a bit far by test driving completed jobs but it's surprising how many issues I actually encounter on the road (as opposed to just running them in the shop)

Unfortunately, the neighbor (it's his car) believes the Volvo dealer 200 miles away can do a better job because they are 'tied directly into sweden'. So out the door it goes - probably taking with it our previously good neighbourly relations.

Sometimes you can't win for trying...

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Best & Thanks;
Marvin

Edited: Sat January 12, 2008 at 6:15 AM by marvin-miller

tony1963 on Sun January 13, 2008 10:01 PM User is offline

We specialize in Volvo and I've had this problem on 850's, S and V70's as well.

I usually find a weak coil in the AC compressor assembly. Since changing the coil requires removing the compressor, we always install a new compressor, pressure cycling switch and AC compressor relay. You'll find the relay in the relay box under the hood, driver's side.

My suggestion would be to simply replace the relay and pressure switch since you have already installed a new compressor. Get the parts at your Volvo dealer, don't use aftermarket.

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Grove Automotive Group, Inc.

An Alabama Corporation

marvin-miller on Sun January 13, 2008 10:29 PM User is offline

Hi guys;

Tony: Thank you for the tips. I did change the pressure cycling switch back to the original OEM unit in an effort to test the system - I ran into the same issue. This afternoon we also swapped the compressor relay from his other nearly identical car and experienced the same issue. (The other car was previously tested to ensure it works on the road!).

Conclusion: It's not the a/c relay nor the pressure switch.

Bohica: We found two thermistor sensors under the front grill pointing directly into the incoming airstream. We took both out and found massive corrosion on both the female socket and the thermistor contacts. I used an ohm meter to measure the resistance of both of them (after extensively cleaning the contacts) and both spec'ed out the same. I then tested against a clean unit from his other (functional) volvo and found the same resistance.

Conclusion: The thermistors in the lower front of the grill are spot on.

New information: If the vehicle is at idle in the shop the A/C works perfectly. On the road the compressor never comes on. Back in the shop the A/C will work perfectly at idle. We then raised the engine RPM to 2,000 and watched to see if the clutch would engage - it did.

As a result we're having a hard time pinning down the problem as it will not act up in the shop.

Any other ideas or advice would be much appreciated. Even a 'dumb' suggestion can cause us to think in a new way ;-) One thing's for sure - it's a wierd issue!

Is there some form of reset procedure that needs to be done on these vehicles? We have disconnected the battery a couple of times in the hopes that it would cause it to operate again. Also, there are no flashing lights on the ECC controls and that seems to indicate that there are no codes present.



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Best & Thanks;
Marvin

tony1963 on Sun January 13, 2008 10:57 PM User is offline

It's actually a very straight-forward system. There is a pressure cycling switch on the low side, a fan switch on the high side and, of course, the control panel.

I have no idea why it would work at idle, but going down the road it won't.

Another thing to check is the push connector where the main power feed goes into the compressor. They get dirty. Spray it out good and see if it is a tight fit. BE CAREFUL SINCE IT IS LOW IN THE ENGINE BAY.

I also check for voltage there with the system calling for cooling. My guess is that you have a bad coil, even on a new compressor.

-------------------------
Grove Automotive Group, Inc.

An Alabama Corporation

Edited: Sun January 13, 2008 at 11:00 PM by tony1963

bohica2xo on Mon January 14, 2008 11:28 AM User is offline

Marvin:

So far you have proven it is temperature relational. When you hear hooves with a Volvo, think tiny stubborn goats...

You say a similar car does not work the same way, but this could indeed be normal operation for this particular vehicle / software.

If you pull that bayonet mount sensor out of it's mount & plug the hole, you can probably test at low temps. You can warm that sensor by warming up a large deepwell socket to about 40c and putting the sensor inside of it - the wrap the whole thing with a shop rag.

I am reminded of why I left northern Colorado for the desert.

B.

-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

cc61 on Tue January 22, 2008 11:50 AM User is offline

air gap needs to be tightened up (even if it is perfect) that seems to be a problem I see alot, If the a/c quits while driving stop (find a safe palce to park) leave engine running , leave a/c turned on, take a long screwdriver and tap the a/c clutch and see if it engages! just a thought

marvin-miller on Tue January 29, 2008 2:02 AM User is offline

Hi guys;

It's snowing up here so we have to wait to test out the A/C. I agree - something's up and the ambient temperature sensor should be the culprit but there's not much point in testing until this cold spell passes and the owner is more enthused :-)

I'll update this thread when we resume work :-)

Thanks!
Marvin

-------------------------
Best & Thanks;
Marvin

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