850 AC - A different problem?

  • Thread starter Thread starter Robert Lutwak
  • Start date Start date
R

Robert Lutwak

The AC on our '96 850 (with fancy climate control) works great for about
5-10 minutes after you turn it on, after which it blows warm air.

The dealer couldn't find any leaks after injecting dye into the system and
looking for it under UV.

I don't think the climate control system is turning off the AC because it's
still running the fan at full on.

What should I look at next ?

Thanks, as always, in advance,
 
Robert said:
The AC on our '96 850 (with fancy climate control) works great for about
5-10 minutes after you turn it on, after which it blows warm air.

The dealer couldn't find any leaks after injecting dye into the system and
looking for it under UV.

I don't think the climate control system is turning off the AC because it's
still running the fan at full on.

What should I look at next ?

Thanks, as always, in advance,
Click to expand...

Is the evaporator drain plugged? On very humid days you should be
able to see the water drip and run out from underneath the middle of
the car.
 
Robert Lutwak said:
The AC on our '96 850 (with fancy climate control) works great for about
5-10 minutes after you turn it on, after which it blows warm air.

The dealer couldn't find any leaks after injecting dye into the system and
looking for it under UV.

I don't think the climate control system is turning off the AC because
it's still running the fan at full on.

What should I look at next ?

Thanks, as always, in advance,
Click to expand...

Robert,
Could be Evaporator icing........
Dale Peterson
 
I was thinking it might be something like that, icing over of the
evaporator.

That isn't the usual sign of failed evaporator, is it?

Is it fixable?
 
Robert Lutwak said:
The AC on our '96 850 (with fancy climate control) works great for about
5-10 minutes after you turn it on, after which it blows warm air.

The dealer couldn't find any leaks after injecting dye into the system and
looking for it under UV.

I don't think the climate control system is turning off the AC because
it's still running the fan at full on.

What should I look at next ?

Thanks, as always, in advance,
Click to expand...
Doesn't the '96 have the infamous compressor overtemp cutout switch? IIRC
they got rid of it in later years, but earlier 850s had the troublesome
switch on the rear of the compressor. They didn't seem to save compressors,
just cause symptoms like yours. The gurus will probably provide the details.

Mike
 
Michael said:
Doesn't the '96 have the infamous compressor overtemp cutout switch? IIRC
they got rid of it in later years, but earlier 850s had the troublesome
switch on the rear of the compressor. They didn't seem to save compressors,
just cause symptoms like yours. The gurus will probably provide the details.

Mike
Click to expand...
Yes but if the car has a pollen filter check this also this will keep
the evaprator from breathing if it is clogged

--
"*-344-*Never Forgotten"
Is for the New York City Firemen who lost their lives on September 11,2001.
The official count is 343, but there was also a volunteer who lost his life
aiding in the initial rescue efforts. And I will never forget them as
long as I live,
nor should any American.
 
The AC on our '96 850 (with fancy climate control) works great for about
5-10 minutes after you turn it on, after which it blows warm air.

The dealer couldn't find any leaks after injecting dye into the system and
looking for it under UV.

I don't think the climate control system is turning off the AC because it's
still running the fan at full on.

What should I look at next ?
Click to expand...

Clutch gap. I've just done mine during the heatwave and bypassed the
temp cutout at the same time. Gap should be 0.3 to 0.5mm and mine was
something like 1.2mm.

It's a bit of a pig to do as I found that I had to remove the ECU's the
ECU box, the belt, the power steering pump, the alternator and the
brackets for same before I could get to the compressor, then the
compressor has to be unbolted to get enough room to take the pulley off
just so that you can remove a shim.

Still it was worth it in the end.

David.
 
Robert Lutwak said:
I was thinking it might be something like that, icing over of the
evaporator.

That isn't the usual sign of failed evaporator, is it?
Click to expand...


If icing was the problem, the airflow would go way down. Also, icing
is usually a sign of low refrigerant charge (At lest it was on my
home's system)

If it's the overtemp switch, the cooling will come and go, over about
a 5 minute cycle. I didsonnected the switch on my 94 years ago, and
haven't had a problem since.

To reply, please remove one letter from each side of "@"
Spammers are VERMIN. Please kill them all.
 
Robert said:
The AC on our '96 850 (with fancy climate control) works great for about
5-10 minutes after you turn it on, after which it blows warm air.

The dealer couldn't find any leaks after injecting dye into the system and
looking for it under UV.

I don't think the climate control system is turning off the AC because it's
still running the fan at full on.

What should I look at next ?

Thanks, as always, in advance,
Click to expand...


My 960 did exactly the same thing, and it turned out to be a $15 temp
sensor at the rear of the engine.

Don't know whether the 5-cyl version of this engine has a similar sensor
/ Motronic setup.
 
Based on the symptoms, I'm guessing it's the overtemp switch on the
compressor. Thanks to all who responded.


Is the overtemp switch a little square molded yellow thingie, about 1cm
square sitting atop the compressor?

Thanks,

-RL

-----
 
David said:
Clutch gap. I've just done mine during the heatwave and bypassed the
temp cutout at the same time. Gap should be 0.3 to 0.5mm and mine was
something like 1.2mm.

It's a bit of a pig to do as I found that I had to remove the ECU's the
ECU box, the belt, the power steering pump, the alternator and the
brackets for same before I could get to the compressor, then the
compressor has to be unbolted to get enough room to take the pulley off
just so that you can remove a shim.

Still it was worth it in the end.

David.
Click to expand...

Another cure for the clutch gap is to put a relay in the circuit. This
gets a higher voltage to the clutch winding, delaying the repair for
???

Disconnect the wire that leads to the compressor clutch.
The wire that's part of the compressor goes to pin 87 on your relay
The wire that's part of the engine harness goes to pin 86 on your relay
Pin 85 on the relay goes to ground.
Pin 30 goes to a fused power source. This circuit only draws about 5
amps.

--
Mike F.
Thornhill (near Toronto), Ont.

Replace tt with t (twice!) and remove parentheses to email me directly.
(But I check the newsgroup more often than this email address.)
 
Robert said:
Based on the symptoms, I'm guessing it's the overtemp switch on the
compressor. Thanks to all who responded.

Is the overtemp switch a little square molded yellow thingie, about 1cm
square sitting atop the compressor?

Thanks,

-RL
Click to expand...

The cutout has 2 wires going into it and is mounted on the back (non
drive end) of the compressor.

--
Mike F.
Thornhill (near Toronto), Ont.

Replace tt with t (twice!) and remove parentheses to email me directly.
(But I check the newsgroup more often than this email address.)
 
Another cure for the clutch gap is to put a relay in the circuit. This
gets a higher voltage to the clutch winding, delaying the repair for
???
Click to expand...

Yes but the amount of effort to do that (and extra pennies) :) when all
I had to do was spend several hours doing it properly just doesn't
compare!

(yeah it's a pig but I like to do things once).

David.
 
Is the overtemp switch a little square molded yellow thingie, about 1cm
square sitting atop the compressor?
Click to expand...

No, it's underneath and round the back, tricky to get to.

David.
 
David Taylor said:
No, it's underneath and round the back, tricky to get to.

David.
Click to expand...

It has two wires, with male and female connectors, which connect
between the car's wiring harness and the clutch wire. All you have to
do is unplug the two connections, and plug the clutch wire directly
into the harness wire.
The connectors have split plastic covers on them which keeps them
clean and secure. Having long, skinny arms helps.

To reply, please remove one letter from each side of "@"
Spammers are VERMIN. Please kill them all.
 
clean and secure. Having long, skinny arms helps.=20

Ah it was the skinny arms that I fail on and besides, I had the
compressor in my hands at the point when I decided to bypass it. I was
already doing the clutch shims.

David.
 
David said:
Yes but the amount of effort to do that (and extra pennies) :) when all
I had to do was spend several hours doing it properly just doesn't
compare!

(yeah it's a pig but I like to do things once).

David.
Click to expand...

While I agree "your" way is the better way to do it, "my" way has some
benefits.
Volvo added a relay for this function on the S/V70 in 1998.
You can do this repair without crawling under the car, or removing any
other parts, a big benefit if it's hot, you don't have much time, or
don't have the tools/skill.
As a disclaimer, I don't know how much longer this will enable the
compressor to work.

--
Mike F.
Thornhill (near Toronto), Ont.

Replace tt with t (twice!) and remove parentheses to email me directly.
(But I check the newsgroup more often than this email address.)
 
As a disclaimer, I don't know how much longer this will enable the
compressor to work.
Click to expand...

That's the thing and with my gap at 1.2mm already, I was going to do
that because the problem only manifested itself during the very hot days
and we don't get enough over here to keep doing trial runs to see if the
fix worked and when it is hot enough, it's a bummer to discover that it
didn't.

Hence, full job for me. :)

David.
 
How do you change the air gap? I've got a VW Passat with similar
symptoms, and am planning tomorrow to try a bypass wire to test with a
solid 12+ volts. If it is the clutch gap, how would it be adjusted? (
Sanden compressor)




Clutch gap. I've just done mine during the heatwave and bypassed the
temp cutout at the same time. Gap should be 0.3 to 0.5mm and mine was
something like 1.2mm.

It's a bit of a pig to do as I found that I had to remove the ECU's the
ECU box, the belt, the power steering pump, the alternator and the
brackets for same before I could get to the compressor, then the
compressor has to be unbolted to get enough room to take the pulley off
just so that you can remove a shim.

Still it was worth it in the end.

David.
Click to expand...

Ron/Champ 6

1963 8E5 Champ (Champ 6)
1962 Lark Daytona Convertible On eBay now...(Boomerang)
1995 VW Passat (Vanilla..yuk)
1994 Volvo 850 (Tilley)
1973 Volvo 1800 ES (Hyacinth Bucket)
 
How do you change the air gap? I've got a VW Passat with similar
symptoms, and am planning tomorrow to try a bypass wire to test with a
solid 12+ volts. If it is the clutch gap, how would it be adjusted? (
Sanden compressor)
Click to expand...

The amazing power of Googling for "sanden compressor clutch gap" yields
the second link as the Sanden service manual
http://www.sanden.com/support/pdf/sd7servicemanual.pdf

Basically, you measure the gap first, remove the clutch then remove the
right number of shims (using your measuring tool such as digital
caliper/micrometer) and then put it all back together again.

The notes say you need to use a clutch puller which you might be able to
hire or slip some cash to the local AC guy etc. I got mine off by just
inserting 3 x 5mm screws and progressively tightening them. They push
against the pulley below which isn't quite the idea but it works. :)

David.
 
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