'98 S70 Erratic air control from ECC or?

Post by **dosbricks** » 03 Jul 2015, 18:56

Greetings P-80 tribe,
A/C blows cold. Original components at 224k. On a very random basis, the ECC will switch from A/C to heat for about 10-15 sec. and repeat this behavior ever few minutes for ten minutes or so. This may happen one day and then skip a day or two. It's more likely to occur on a drive of 20 minutes than a short run to the market. The dampers seem to function correctly. Based on that, I figured maybe the ECC was at fault since I had had a failing one on my 850 wagon and a used unit set it straight.

Since there are no junk yards with an S70 within 100 mi., I got a clean-face used ECC from an ebay JY for $18 (cheap because it was missing the little knob on the fan-speed slide-control which I easily swapped onto it from the original unit). It functions--but with the same proclivity for wigging out every so often.

So either both units have the same fault, or perhaps a signal receptor is going south. BTW, there are no flashing lights or other fault indicators. My code reader is an Innova 3100. I don't think it will pull A/C codes. Unfortunately, I have limited electrical diagnostic capabilities, so I turn to those who have trod this path before me.

dos

Post by **abscate** » 03 Jul 2015, 19:03

Classic AC compressor clutch gap failure.

Bread clip fix, although zip ties are becoming in vogue now.

Search " bread clip fix"

Post by **dosbricks** » 03 Jul 2015, 19:40

abscate wrote:Classic AC compressor clutch gap failure.

Bread clip fix, although zip ties are becoming in vogue now.

Search " bread clip fix"

Thanks Steve, but I already did the clip fix on this car about a year ago. But tomorrow I will check to see that all three clips are still in place and the gap is still in spec.

Post by **scot850** » 03 Jul 2015, 19:59

It will most likely be one of 2 items:

1) Fan motor varying, but as you would probably notice this it is most likely:
2) The cabin temperature sensor in the dash. It sits behind the little grille to the left of the ECC controller. To access it, pull the radio ( having code available), pull the ECC (you already know how to do that also). Now to the left of the ECC 'hole' sits a little fan assembly that sucks cabin air past a little temp. bead that adjusts the cabin temp appropriately to that set in auto mode. The little fan assembly clogs up with airborne 'stuff' and the fan stops drawing the air through. These units also fail. Removing it a swine if you haven't done it before. There are 2 compression clips on the body of it that need to be compressed to remove it from behind the dash and an electrical connector. I had one of these start to fail and this is the exact problem it caused.

If you are lucky, gentle cleaning with cotton buds and some IPA, and then a light spray of light oil can sometimes help if it is not too far gone.

: Cabin temp controller

: Temp controller #2

In the 2nd picture (sorry they are a little blurred, no alcohol consumed in the taking), you can see one of the 2 compression clips. The 2nd is 180 degrees from there. Be patient and wear long sleeves as the ECC hole can be rough.

Neil.

Post by **dosbricks** » 04 Jul 2015, 13:23

Steve, Neil, both you guys gave excellent advice. the clutch had indeed tossed a clip and was running (or sometimes not) on two. I'll fix this tomorrow--holiday stuff going on today.

I did remove the temp sensor and it had a whole lot of lint in there. I brushed it out with a little 1/8" tapered bottle-type brush. Afterwards the motor seemed to rotate more freely. I attempted to take the motor apart (5 tiny clips) to lubricate it. Not possible, since the temp sensor wires are threaded through the fan housing and then crimped and fused together, so not advisable to try that lest damage ensue to sensor.

Afterwards, the A/C was working and when I turned it off and set the blower fan speed to zero, I could hear the sensor fan running by getting my ear close to the grill. With a flashlight, I could observe it start and stop when the engine was started and turned off.

So as soon as I replace that lost clip, I fully expect everything to be copacetic once again. Many thanks for the expert guidance--and happy 4th of July!

dos

Post by **abscate** » 05 Jul 2015, 04:00

Excellent...the thought of a car without AC in a TX summer was unpleasant...

Post by **erikv11** » 05 Jul 2015, 08:42

Ditch the bread clips, go with zip ties. The zip ties don't fall out/off.