A/C air flow cuts in and out, this sounds specific

cquarts · Post by **cquarts** » 24 May 2010, 07:58

I put this problem up several months back but I hope based on the perculiar way this can be relieved that someone has an answer. While the a/c is blowing cold air sometimes it will just stop blowing. But, if you take your foot off of the gas pedal it starts to blow again. This, in my limited knowledge, does not sound like the air flow switch. It sounds more like a vacuum issue ? but I have checked the hoses as much as possible and cannot find any leaks. Any ideas? Please help. It gets hot in Georgia. Thanks

Post by **billofdurham** » 24 May 2010, 15:28

Model and year of car? Manual climate control or electronic?

Bill.

Post by **billofdurham** » 25 May 2010, 12:53

It has been determined that this is a '95 940 turbo with manual controls.

The attached shows the VADIS diagram of the heater with four vacuum bellows, three of which are on the left side of the heater and the fourth on the right. As the problem seems to be vacuum related it is necessary to check, very carefully, every vacuum pipe attached to the heater. Also check that they are a good, tight fit on the connectors. Page 4 shows what each colour pipe does.

940 Heating and vacuum controls.pdf: (125.96 KiB) Downloaded 1248 times

I hope this helps.

Bill.

adki110 · Post by **adki110** » 26 May 2010, 19:02

I had the same problem with my 1992 940. One of the diaphrams on the the left side of the consol had ruptured. Being one of the lazier of the species, I would disconnect and plug the yellow vacuum tube in the summer and reconnect it in the winter.

lru · Post by **lru** » 27 May 2010, 17:50

I have a similar problem and also think it gets hot in Georgia. My car is a good looking and well running volvo 760 with 170,000 miles on it. I actually put another engine in it a couple of weeks ago and it is doing fine. Although the air was working quite well right after the work was done, the air flow stopped coming out of the top dash vents. It is still very cold, and only comes out the floor vents and side window vents. I'm wondering if I put the vacuum lines back together right? I think so, but could use some advise on this.

Post by **billofdurham** » 28 May 2010, 12:21

Iru, welcome to Matthew's Volvo Site.

The attached is a simplified diagram of the 760 ECC vacuum controls and pipe colours and destinations.

760 ECC vacuum controls 1.pdf: (512.46 KiB) Downloaded 148 times

The ECC also has a built in diagnostic function which can be used to pinpoint other faults.

Bill.