UKKid35

Does anyone know of a direct replacement for the dodgy relay?

Or can anyone provide the pin layout?

Many thanks

Rob Edwards

https://rennlist.com/forums/showthre...ighlight=relay

UKKid35

Thanks Rob, sorry for not searching properly...

Bill Ball

AFAIK, there is no direct, drop-in replacement. The thread Rob linked discusses some oddities with the stock relay depending on MY. Your controller should have the blue Gruner 202, and the Radio Shack 275-218 is a commonly used substitute. It's larger, so it must be wired to mount remotely, stuck to the outside the headunit case ( I used hot glue).

UKKid35

This one looks like the specs would be suitable, but the pin layout isn't even close

http://www.willow.co.uk/HG4527.pdf

Thanks for all the detailed info in your original thread

UKKid35

I didn't get around to changing the dodgy relay before a trip to Italy, big mistake! In the UK where I only used the aircon in relatively short bursts of 20 or 30 minutes the problem with unreliable relay was hardly noticeable, but south of Switzerland it became very obvious.

We found it neccessary to use the aircon for hours on end, and the relay couldn't cope, and neither could we without the aircon in 35deg plus. I hoped that the relay was being overheated by the compressor clutch current, and not the relay coil itself, and so I found an autoparts outlet near Verona (no mean feat in itself), and set about wiring an additional fused relay in series taking power from the +ve post under the bonnet. This worked perfectly, as did the rest of the system (which is filled with Isceon49).

I will eventually replace the relay in the HVAC controller but, without this workaround which I put together in a campsite in Verona, our trip would have been far less enjoyable.

Alan

I prefer to add a standard relay for the clutch on the central electric panel - there is always at least one slot free. This makes it a very capable 30A+ relay switching the clutch (and easily replaceable). Unfortunately the relay in the head unit has 2 parallel contact sets so you really still need to change that relay also... unless you can determine that the other contact set still works ok. In this case you need to wire the coil connection to the output terminal and use that for the new relay coil connection.

I consider this to be a good preventative measure - if your relay is still fully operational you can make this change on the back of the Central Electric Panel without touching the HVAC.

None of these miniature relays is really up to the job - its a weak point in the design.

Alan

dr bob

This points to a issue that is becoming very common. The AC control head relay is something that will fail. There's no question. So owners need to decide when to fix it. How about --soon--, even if the AC still seems to work OK now. Maybe the annual electrical maintenance list needs to be modified slightly, so that right after "clean the ground points" there's a task something like "AC control head relay replace if it hasn't been already." These relays only fail in the summer when you need them, when you are farthest from home and have no tools, pretty much at the most inconvenient time. Like any other electrical failure. What are the odds that you'll want to use the AC while sitting in the home garage in winter when it's way too easy to fix?

dr bob

Good point! The second contact pair in the head relay sends the 'ac running' signal to the setting motor controller IIRC. I looked at it and think you could pretty easily add a diode to do the second contact duty. That would enable the CEP relay option with a more standard plug-in relay that would fit a spare socket position. Electrical Guru Alan can tell us if my foolish diode anaylsis is accurate.