2001 S40 A/C only blows on high or off

[regent]

I noticed you are actually using a Volt-Ohm meter (which is fine).

Make sure your reference 'ground' point is good. I'd suggest connecting the negative lead of your meter to one of the ground straps in the engine compartment or better yet - to the battery negative terminal, and then redo the voltage readings.
If the climate controls are not working, are any of the indicator lights on the CCM working, if yes, are they changing state?

[grileaux]

For the ground, I used a screw that holds the metal step to the door frame. Its pictured above.
No,neither the climate control nor the the indicator lights are working.
Is there a test i can use to see if my ground is good?

[grileaux]

The negative on my meter won't reach the battery. I'm trying to locate ground straps in my engine compartment.

[regent]

You could use a lenght of insulated wire to extend your negative.
To verify that your grounding point is good, the best way would be to connect a small light bulb to the ground point in question and a known good source of +12V (just be very careful not to make a short).

Safety First: I would recommend reading some general electrical troubleshooting hints here: http://www.aa1car.com/library/tselec.htm
Hope this will help you with safety and make you feel more confident in what you are doing.

Let us know.

Oh, if your Climate Controll Unit seems to be dead (no lights no response) this could be the only culprit

[regent]

A search on the forums returns this thread that may be helpful:
https://www.matthewsvolvosite.com/forums ... =8&t=19450

[regent]

Also, there seems to be a related Volvo recall, check to see if the fix has been already done on your car: http://www.justanswer.com/volvo/577x4-v ... -does.html

[grileaux]

So, I'm reviewing the troubleshooting link you've sent me, thanks for that. That link also took me to another helpful guide for understanding relays.
Unfortunately, my computer will not go to the other S40 forum that I was directed to by your link to the related forum on our site, the computer is telling me its an invalid URL or dead link.
Also, I just got off the phone with my local Volvo dealer and I've been told that the recall you told me about has been serviced on my car. That would have been cool to have them fix the recall and solve this issue for no charge to me, but where's the fun in that.?

[regent]

Awesome - one suspect is down (the recall that is).
We don't know for sure if more 'mods' (like the jumper) may have been introduced by the previous owner.
I saw that your AC Compressor Clutch 8/1 is controlled by the EMS (Engine Mgmt System) via relay 2/10 and you know it is working. I am not sure if the clutch would engage with CCM being ‘dead’ but it would not hurt if you can confirm that your 'unresponsive CCM' is getting power at all. On pages 6 and 60: fuse 11A/8 powers a long list of things (among which CCM) and if they are working, the fuse is good…
Keep going and let’s hope that someone with hands-on experience with your car and problem will jump in soon.

[grileaux]

I re-administered the voltage test, using the negative jumper cable wire and connecting that to my voltammeter and negative post of my battery (pictured below). (with the ignition turned to position II) The results are as follows;
Pin 2 DCV 79.1
Pins 3 and 4 both .007 ACV with no change when adjusting climate CTRL knobs.
In checking my fuse boxes, the only blown fuse I found goes to the vacuum pump, and I'll be ble to replace that later this afternoon.

Do you think that using my jumper-cables is a sufficient ground for testing the voltage?

[regent]

First, here is some good stuff on the vacuum pump in the forums:
https://www.matthewsvolvosite.com/forums ... =9&t=43817
(your fuse is blown most likely for a reason)
For the purposes of a voltage test, your reference (negative, ground) point looks excellent to me.
The readings: Pin 2 is supposed to read zero at all times (it is hard-wired to ground at 31/1 via JP 43/401) I would assume you are reading 79.1 millivolts (0.0791 VDC) which is quite close to zero.
If all is good and working, the potential on Pin 4, will have both DC and AC components and depending on the blower speed, will vary from battery voltage (approx. 12 VDC with the blower at zero speed) all the way down to zero VDC at maximum speed. At max speed, the relay 2/19 is picked up and its contact (4, 2) is closed, which connects JP 43/400 to JP 43/401, which we know is grounded at 31/1. This would be the case with all good and working. Now, if CCM is bad or just not getting power, it would not command 2/19 to close. You want to confirm that the connectors to CCM are snug before condemning the module. Since you have no lights and no control pulses on speed regulator ‘resistor’ Pin 3, the CCM is a suspect. But check to see if it’s getting power first. Before removing any connectors and/or fuses, make sure you have the Battery Disconnect/Reconnect Procedure and follow it