Volvo 740 GL 1990 Air Conditioning

[V7401990GL]

Have recently acquired a 90' 740 GL, the air conditioning clutch does not engage when turned on inside the cab, could it be that I need to re-gas the air conditioning system for the clutch to engage or is this an indicator of another issue?

[Laird Scooby]

Originally Posted by V7401990GL

Have recently acquired a 90' 740 GL, the air conditioning clutch does not engage when turned on inside the cab, could it be that I need to re-gas the air conditioning system for the clutch to engage or is this an indicator of another issue?

Is it manual or ECC (Electronic Climate Control) air conditioning?

[V7401990GL]

How can I tell?

[360beast]

The heater control panel will have auto settings for ecc and just a button for air con in a normal air con system.

It is probably a lack of air con gas as the lack of pressure will be picked up by a sensor which prevents the clutch from kicking in. You may find if you regas it that it leaks out very quickly, usually the condensor is rotten or the clamp on the condensor doesn't have a tight seal due to worn out o-rings.

[V7401990GL]

its just got a button

[Laird Scooby]

That's the manual system then, first check all the fuses linked to the AC system including for the auxiliary electric cooling fan in front of the condensoer and radiator.

If everything looks ok and it's still not clicking the clutch in, identify the feed wire to the clutch on the compressor, get yourself a jumper wire and connect to it then tap the other end on the battery +ve terminal. If you hear it click, repeat the test with the engine running to make sure it doesn't make any horrible noises.

If so, chances are you'll get away with a recharge kit but make sure you have an R134a system and not and R12 before buying this kit or similar :

https://www.ebay.com.au/itm/284664407044

I haven't read the full listing so make sure the recharge gas canister also has some oil in it for the compressor etc and preferably a leak sealer too.

If none of that appeals or you have an R12 system, you'll probably need an AC specialist to convert the valves to R134a, vac the system down (consider renwing the reciever dryer too!) and check for leaks then recharge the system with gas and test before handing it back to you.

Good luck and let us know how you get on!

[Clan]

Originally Posted by Laird Scooby

That's the manual system then, first check all the fuses linked to the AC system including for the auxiliary electric cooling fan in front of the condensoer and radiator.

If everything looks ok and it's still not clicking the clutch in, identify the feed wire to the clutch on the compressor, get yourself a jumper wire and connect to it then tap the other end on the battery +ve terminal. If you hear it click, repeat the test with the engine running to make sure it doesn't make any horrible noises.

If so, chances are you'll get away with a recharge kit but make sure you have an R134a system and not and R12 before buying this kit or similar :

https://www.ebay.com.au/itm/284664407044

I haven't read the full listing so make sure the recharge gas canister also has some oil in it for the compressor etc and preferably a leak sealer too.

If none of that appeals or you have an R12 system, you'll probably need an AC specialist to convert the valves to R134a, vac the system down (consider renwing the reciever dryer too!) and check for leaks then recharge the system with gas and test before handing it back to you.

Good luck and let us know how you get on!

It has been illegal since 2010 for anyone to tamper with car AC systems , there are defined processes and the operator has to have a Certificate and be on the list of Authorised AC technicians . The fine for letting any ac gas out into the atmosphere is up to £40,000.