Had the A/C filled on Friday but he had trouble getting the gas in. The compressor is working fine but the radiator fan wasn’t cutting in. I’ve hooked it up to MES today and tried the activation of both single and double speed by there’s nothing.

I’ve connected the life and earth direct to the battery and it spins fine so it’s not the fan itself. I understand the Dan gas a fuse/relay number 7 in the under bonnet fuse box so that may have gone but there’s no way unlike a conventional fuse to check it. I also originally thought it might be the resistor but would the resistor even stop it from working entirely if it was faulty or missing?

Checked the relays?

John202020 said:

Checked the relays?

Click to expand...

6 and 7? Well how? I changed the smaller one but the spate fusebox I have comes from a Pop without the big one. How do you check them?

Are you sure the compressor is compressing? Hand on pipe should be freezing ,note too much/little gas causes the system to trip out.
If it is compressing and does so for a while rather than lots of very short on offs then it's back to working out why the fans don't run, does it come on when the engine is toasting?
The cooling fan should come on with the compressor when it makes a pronounced click(on)

Relays usually 4 contacts two is the switch terminals the other two is the coil that makes the relay operate using a meter you can work put what's what, often it's marked on the top which is which

John202020 said:

Are you sure the compressor is compressing? Hand on pipe should be freezing ,note too much/little gas causes the system to trip out.

If it is compressing and does so for a while rather than lots of very short on offs then it's back to working out why the fans don't run, does it come on when the engine is toasting?

The cooling fan should come on with the compressor when it makes a pronounced click(on)

Click to expand...

Yes it’s compressing but the fella who does my gassing said he managed to eventually get about 400 grams in out of what should be 500. It’s cold although difficult to tell properly in this weather. It’s clicking in and out as I remember others do. The engine went over the half way mark in tick overs while gassing and the fan didn’t cut in at all.

So if I put a meter on the pins I should get something?

Would the lack of, or a broken resistor stop it working completely?

You should get nothing on two pins and about 100-400 ohms on the other two a small 9v battery can be used to test it.
The resistor may stop it working at slow speed but is usually bypassed when running on high.
Placing a finger on the relay it should click at the same time as the compressor, if it does suspect the resistor

You can pull the relay out then bridge the connections directly, if the fan kicks in then the signal to the fan is not coming through or the relay is knackered.

You can put a meter on the switched live of the relay and then cycle it on and off from
Mes you should see 12v appearing and disappearing on the meter. Is there a relay on the fan shroud to switch between high and low speed, I don’t know the wiring layout of the 500. There is usually a relay to turn the fan on and off and another to control the speed via a resistor

Relay 6 is the slow speed one 7 is the high as far as I can see, if the resistor has failed it won't run on slow try shorting out the resistor pack terminals?
F06 is the slow speed fuse
F07 is the high speed fuse
All going from the Haynes manual

The two speed fans have a resistor the single speed fans don’t.

There are no other switches or relays apart from the two in the fuse box.

I’ll have a play tomorrow but I’m hoping that it’s just the resistor. I’ve ordered a new one. Fingers crossed.

Good news. The new resistor arrived today, fitted, fired up the A/C and bobs your aunties live in lover. All working.