air conditioner

RAMBLER67 · Post by **RAMBLER67** » 14 Sep 2009, 12:25

1986 volvo 740 gle wagon (location midstate Arkansas)

air conditioner: no power to compressor
compressor/clutch, low pressure switch,engine compartment wire good
run fused jumper from hot source system works
cabin area trouble finding the feed wire
help!!
basic unit( switch panel:fan switch/temp lever/vent position lever)
ambeint air/heat/fan speeds/vent positions work
air was working then just lost power to compressor

Post by **billofdurham** » 18 Sep 2009, 15:55

Welcome to Matthew's Volvo Site.

If you hot wired the compressor and it worked I should think that the system is low on refrigerant. This would stop the compressor to avoid damage.

Bill.

RAMBLER67 · Post by **RAMBLER67** » 21 Sep 2009, 07:22

compressor pressures are good
when you turn system on no power to the compressor
traced wire back:compressor to low pressure switch to were it enters thru firewall, no damage and no "juice"

Post by **billofdurham** » 22 Sep 2009, 11:59

compressor pressures are good

With what and how did you check the pressures?

Bill.

RAMBLER67 · Post by **RAMBLER67** » 22 Sep 2009, 12:36

Took a fused (fuse removed) jumper wire tied it to feed wire to low pressure switch, started car turne fan switch on #3, set control to "snow flake" no power to low pressure switch. At this point put fuse in on feed wire clutch locks in, hook up air conditioning gage/lines, pressures read text book.
All functions work from control panel except power to compressor clutch

No power from heat/air controller panel to air compressor

RAMBLER67 · Post by **RAMBLER67** » 22 Sep 2009, 12:45

The problem I am having is tracing the feed wire after it goes thru firewall in the cabin, controller do not see the same color wire coming out of it as under the hood. Not wanting to go a "finger-around in that twisty knot of wires and vacuum lines (break a contact point or unplug one a nd pay he_ _ trying to find and fix it!!
Does the wire once it goes thru the firewall have a junction and change colours by chance (my 68 Dodge Polara wiring does this)

Post by **billofdurham** » 24 Sep 2009, 15:57

My wiring diagram shows that the wire from the pressure sensor to the switch on both manual and auto climate controls is green all the way. From the pressure sensor to the compressor is the same.

Pleas refrain from using all capital letters in your posts as we class this as shouting.

Bill.

RAMBLER67 · Post by **RAMBLER67** » 25 Sep 2009, 07:46

Thank you
Does the green wire go to the fan switch?
Mine does not have a green wire
or
does the fan switch and vent location lever (vacuum port) activate a relay or solenioid down line that the green wire goes to?

As for capitals, I am 30+ year draftsman/engineer (mechanical) all drawings capital lettering (even cad dwg) hard to break a programed procedure/habit; started out in drafting class junior high/high school 4 weeks each of lettering,capitals.
Even written reports
Will try to remembeR
Thanks Agian

Post by **billofdurham** » 25 Sep 2009, 12:21

The attachment has the wiring diagrams for both auto and manual AC. These are taken from a Volvo publication and do refer to US market cars.

740 AC wiring.pdf: (729.87 KiB) Downloaded 404 times

I hope this is of some help.

Bill.

RAMBLER67 · Post by **RAMBLER67** » 25 Sep 2009, 12:36

Yes Sir!!
thermo switch is what I need to locate

Next question,idea were it is located? See nothing on under hood or behind switch panel

Thanks!!