1994 940 cooling fan never comes on

[Free940]

Originally Posted by aardvarkash10

You see Grasshopper? Patience...

Exactly!



"Blip" the throttle to get the engine up to about 3,000rpm and then back to idle. Does the sound of clicking stop when you close the throttle?



The could be old codes. Take fuse #1 out of the fuseholder for 1-2 minutes, then replace it. This clears any old codes. Run the car and then recheck the codes.

It got dark and the mosquitoes were swarming. I will try those ideas tomorrow. It is still doing that sudden cut off thing. It will be running fine for a long period and then suddenly it dies like an ignition issue(?). Oh well, another challenge.

[aardvarkash10]

Originally Posted by Free940

It got dark and the mosquitoes were swarming. I will try those ideas tomorrow. It is still doing that sudden cut off thing. It will be running fine for a long period and then suddenly it dies like an ignition issue(?). Oh well, another challenge.

When it dies next, watch the tacho. If it drops like a stone (rather than following the engine rpm down), its likely one of only three things.

[Jebus]

I'll put my 2p on the crank sensor being iffy

[Laird Scooby]

Originally Posted by Free940

It will be running fine for a long period and then suddenly it dies like an ignition issue(?). Oh well, another challenge.

Obtain some heatsink compound and a solvent cleaner (rubbing alcohol or similar) then locate the ignition amplifier module on a heatsink on the left hand inner wing/fender behind the headlight.

Unplug and remove the two screws to remove the amplifier module.

Clean the back of it (aluminium) with a non-fluffy cloth and alcohol - DO NOT USE ANYTHING ABRASIVE!!!!!

Do the same to the heatsink where the module is fitted.

Once clean and dry, smear some heatsink compound on the back of the module and position on the heatsink - wiggle it about a bit to spread the compound evenly then refit the screws and plug the connector back on.

Follow the harness from it towards the suspension tower, you should find an earth connection screwed/bolted to the panelwork. Remove, clean with a wire brush, emery cloth or similar and refit.

Besides being preventive maintenance, this will rule out the ignition amp module from the diagnosis and may cure the problem. If the problem is cured, that was the problem. If it isn't solved, look at the CPS and also the fuel pump fuses, #11 and #13 if memory serves on the 940 but Ash will confirm that.

Even if the fuses look intact, if the blades on them seem even remotely dirty, renew them.

[Free940]

Originally Posted by aardvarkash10

When it dies next, watch the tacho. If it drops like a stone (rather than following the engine rpm down), its likely one of only three things.

Originally Posted by Jebus

I'll put my 2p on the crank sensor being iffy

Originally Posted by Laird Scooby

Obtain some heatsink compound and a solvent cleaner (rubbing alcohol or similar) then locate the ignition amplifier module on a heatsink on the left hand inner wing/fender behind the headlight.

Unplug and remove the two screws to remove the amplifier module.

Clean the back of it (aluminium) with a non-fluffy cloth and alcohol - DO NOT USE ANYTHING ABRASIVE!!!!!

Do the same to the heatsink where the module is fitted.

Once clean and dry, smear some heatsink compound on the back of the module and position on the heatsink - wiggle it about a bit to spread the compound evenly then refit the screws and plug the connector back on.

Follow the harness from it towards the suspension tower, you should find an earth connection screwed/bolted to the panelwork. Remove, clean with a wire brush, emery cloth or similar and refit.

Besides being preventive maintenance, this will rule out the ignition amp module from the diagnosis and may cure the problem. If the problem is cured, that was the problem. If it isn't solved, look at the CPS and also the fuel pump fuses, #11 and #13 if memory serves on the 940 but Ash will confirm that.

Even if the fuses look intact, if the blades on them seem even remotely dirty, renew them.

Thanks Guys! Some great info to keep me busy! I will keep y'all posted.

Dave, I just happen to have a brand new tube of heat sink compound.

[Free940]

Hope i'm not wearing out my welcome..

As soon as I got home I started working on the Volvo.

I had wanted to get the air conditioner working, but then I figured I had better see if the engine would even start.. Spun it over.. No go. I then decided to check the crank sensor connector.. a little green, so I cleaned it up nicely and gave it another try.. it spun over but would not crank.. I moved on to the ignition amplifier module. I removed the top of the air box for access. I left the heat sink mounted and just removed the module.. As soon as I unscrewed the module to lift it out, the connector fell off! It was not tightly plugged in. Also the contacts were green. I cleaned the contacts up and put some fresh heat sink compound on the cleaned surface and screwed it back on. Made sure I had a good ground. Engine started right up and never shut off again despite starting, restarting and letting it run for extended periods. I truly believe that was the problem.

Moving on to the air conditioner. The fan is blowing, but no cold air. I checked the low pressure switch.. I have a closed contact. I then checked for voltage on the low pressure switch connector.. zero volts. I unplugged the clutch wire going to the compressor and when I applied 12 volts.. the clutch would click on.. I even tried it while the engine was running.. the compressor would pump or at least spin. I then checked what I believe to be the (purple) high pressure switch located on the condenser. Closed circuit. I looked at all the fuses and none of them mentioned the AC system other than for the blower motor. One thing that was peculiar.. the heat is also not working. Any ideas?

[Free940]

After looking at a wiring diagram, everything is pointing to the climate control module, 6848302 (?) I need to pull it out and take a peek..

[Laird Scooby]

Originally Posted by Free940

After looking at a wiring diagram, everything is pointing to the climate control module, 6848302 (?) I need to pull it out and take a peek..

Not necessarily. Are you getting any air out of any of the outlets whether that's the screen, footwells or dash vents? If so can you vary that temperature to cold (or as cold as you're likely to get without A/C)? Does the Recirc button work?

If the answer is "No" to any of those but especially 2 or more of them, the chances are the solenoid valve block that switches various valves on that then provide vacuum to operate the various valves that operate vacuum servos to change temperature, direction of air, recirc flap and the heater control valve under the bonnet.

This solenoid valve block is in the heater assembly :







As you can see, you need to remove the glovebox and under-dash trim on the passenger side for access. The close ups of the circuit board are where the solder has cracked, remove it with a solder sucker and a little flux (tip - if you don't have any flux, add some fresh multicore solder while desoldering and the flux from that will do) then resolder with fresh solder.
On mine the worst dry joint was actually the main power input to the solenoid valve block so none of the valves would work.

For clarity, it's the module with the different coloured vacuum tubes, it's a few years since i did mine so can't remember all the details, should be enough information there for you to find the modeul, open it up and check it/repair it.

Good work on the igntion amp module too!

[Free940]

Thanks for the detailed info.

Just to clarify, the only problems with my climate control is that the AC is not blowing cold air and there is no heat. All the outlets are switching as they are suppose to when I turn the knob. The air is being redirected to the proper outlet. When I turn the temp control from cold to hot, there is also a change. I can hear something happening, but the air blowing out remains the same temperature. Nothing happens when I press the recirc button (that I notice) and, of course, pressing the AC button has no affect.

I did repair a serious vacuum leak on some device under the intake manifold, towards the firewall, by replacing a rotted curved vacuum line, but I don't know it's purpose, nor did I try the heater after the repair. It may very well be the heater control valve, as I just looked at a picture and it is similar looking.

The ignition amp module is still giving me problems. Someone has buggered up the connector. There is no metal clip and some of the plastic connector is missing. (how did they manage to do this?) I tried to use tie-wraps to secure the connection without success. There is nothing solid to wrap the tie wraps around without interfering with the heat sink. I plan on just squeezing the connector tight and using some electrical tape.

[Laird Scooby]

Originally Posted by Free940

Thanks for the detailed info.

Just to clarify, the only problems with my climate control is that the AC is not blowing cold air and there is no heat. All the outlets are switching as they are suppose to when I turn the knob. The air is being redirected to the proper outlet. When I turn the temp control from cold to hot, there is also a change. I can hear something happening, but the air blowing out remains the same temperature. Nothing happens when I press the recirc button (that I notice) and, of course, pressing the AC button has no affect.

I did repair a serious vacuum leak on some device under the intake manifold, towards the firewall, by replacing a rotted curved vacuum line, but I don't know it's purpose, nor did I try the heater after the repair. It may very well be the heater control valve, as I just looked at a picture and it is similar looking.

The ignition amp module is still giving me problems. Someone has buggered up the connector. There is no metal clip and some of the plastic connector is missing. (how did they manage to do this?) I tried to use tie-wraps to secure the connection without success. There is nothing solid to wrap the tie wraps around without interfering with the heat sink. I plan on just squeezing the connector tight and using some electrical tape.

Would be worth checking the operation of the heater valve, under the bonnet near the bulkhead with a vac hose running from it. Without vacuum it should be open but if it failed in the close position (for blowing cold air) then it may not open properly. You can do a temporary bypass with some 15mm (9/16") water pipe or similar to prove whether it's that preventing heat from the heater.

You can buy the connector housings from Volvo, this isn't the right page, if you look at the parent directory for this page you should (with time and patience!) find the right one but it might be easier to phone your local Volvo dealer.

https://www.volvopartswebstore.com/s...rimLevel=24652

Hopefully you can find the right bits one way or the other, chances are the previous owner broke it trying to work out why it wouldn't start.............