Topic

Hi all, hoping you can help!

Today I had an aircon regassing service round to do three cars, the MGF was found to still have gas in and was pressure tested - all was fine. However, once refilled and tested, there was a shout of "Turn it off quickly!" from the operator. It would appear that the fan wasn't cutting in and so the system had heated up hitting 300psi pressure. Luckily, it didn't blow the system.

Now I'm sure that the fan was working a few weeks ago as I checked it after doing a radiator change - switched the aircon on and the fan worked. Now there's nothing. I've checked the fuses in both fuse boxes and they're fine. I also checked the relay behind the fuse box under the bonnet to find that there isn't one, just a black plastic and metal bridge piece that looks made to bridge two connections. Is this thing normal or has it been bodged in the past? I've heard you can use the relay for the electric windows to test the fans which I'll give a go, but I can't work out why it appeared to work the other week and now doesn't and why this weird bridge is there!

Any help or thoughts are greatly appreciated!

The bridge is correct, the relay is replaced by the two plug relay pack to the side of the fuse box.

To test both cooling fans you need to take off the engine cover to access the coolant temp sensor (blue or black) and unplug it, then start the engine and both front cooling fans should come on.

I assume you are switching on the internal fan as well as the A/C switch, this is when the front cooling fans come on.

Hi, yes, the internal fans are on full whack. Am I right in thinking switching on the AC should fire the fans up normally?

The two radiator fans do not come on automatically when the AC is turned one. The operation of the two fans is controlled by the AC relay pack that James mentioned, as well as, the trinary switch located at the top of the dryer. At a predetermined pressure, measured by the trinary switch, the fans turn on. If the pressure continues to rise, the fan speed is increased. If the pressure still continues to rise, the ECU turns the system off automatically.

Given that you just had the AC system serviced, I'd check the trinary switch wiring connection at the dryer.

Sorry for the slightly ungrateful lack of reply thus far! I should get a chance to take a look over the weekend. I'll report back when I've had a good check about!

Thanks for the advice all!