31 replies to this topic

[Gary33031]

Can anyone advise regarding a problem I am having with my AC. My compressor cycles on and off. There is an AC relay YWB101080 which I can't locate. Can you advise where in the car I would find this relay and where I might be able to find a replacement. If anyone has had this issue, how were you able to resolve the problem?

[Steve220]

The relay itself is in the relay module on top of the brake servo. It is no longer available. I've just tried searching through the ether of the internet and not coming up with anything.

[xrocketengineer]

Have you serviced the refrigerant? My understanding is that the system has a low pressure switch and a high pressure switch like many other cars. Under normal conditions (full refrigerant load), the low pressure switch shuts off the system to prevent freezing of the cooling coils as the temperature in the cabin goes down. If the system is low in refrigerant, the pressure will go down in the suction line very quickly and the system will shutdown even though the cabin has not cooled down. As soon as the pressure stabilizes (pressure back up) the system kicks back in and starts to lower the pressure again in the suction side. The less refrigerant in the system, the quicker the compressor cycles on and off.

The high pressure switch prevents the system from blowing up due to too much refrigerant, clogged up system or the external temperatures are so extreme that the condenser can not cool down the refrigerant enough.

Any A/C shop should be able to check your system here in Florida. It uses standard fittings and R134A. Or you might want to try something like this, if you know what you are doing:

 

The pressure should be around 35 psi at about 2000 RPM. Be aware that working with refrigerants is hazardous.

http://www.autozone..../?checkfit=true

[Gary33031]

Pressures have been check with gauges on both high and low side. It's definitely an electrical problem. Could be a bad relay or a short somewhere. System works intermittently. When it's working it blows ice cold. It would help if I could find a manual for a Japanese Rover SPI 1997, that includes the AC system. If you know where I might find a manual, please advise.

[xrocketengineer]

The manuals are here in post #40 for all the MPI and for the SPI post #71 since the MPI one is missing some generic stuff:

 

 

http://www.theminifo...-perhaps/page-3

[FlyingScot]

The relay itself is in the relay module on top of the brake servo. It is no longer available. I've just tried searching through the ether of the internet and not coming up with anything.

Steve not sure that's right, my engine MFU is on top of the servo but my a/c relay is under the dash rail on the rhs just near the bonnet pull (JDM 35th Anniversary Cooper).

FS

[FlyingScot]

In fact it looks like an engine one but mine is white....

FS

[Steve220]

The relay itself is in the relay module on top of the brake servo. It is no longer available. I've just tried searching through the ether of the internet and not coming up with anything.

Steve not sure that's right, my engine MFU is on top of the servo but my a/c relay is under the dash rail on the rhs just near the bonnet pull (JDM 35th Anniversary Cooper).
FS

Oh right! Think I may have been confused by the wiring diagram and a bit of assumption on my part.

[Gary33031]

I need to spread the word to see if I can find the AC relay. I can't believe no one has one. Please ask you friends and club members.

There has to be at least one of the the relays sitting on a shelf or in a box in someone's garage. Please see if you can help me out.

Most important one is the AC system relay

YWB101080 Relay AC System

YWB 100680 relay evaporator

Any help you could provide would be greatly appreciated. Also if you know of an alternative source, please advise.

Thanks,

Gary MacDonald
Homestead Florida ,

Edited by Gary33031, 23 May 2016 - 01:45 AM.

[FlyingScot]

Gary why do you think it is the relay? The format of these TRW (formerly Lucas) relay units are essentially the same, with signal wiring on one side and the power circuit on the other. It might be worth back probing the signal side to see if it is switching the power side on and off (thermostat or pressure switch problem). The open frame relays themselves can be replaced in these units (I have done so in the ECU MFU before now). Either a multimeter or good auto electrician should be able to confirm why its switching on and off?

FS

Edited by FlyingScot, 23 May 2016 - 07:21 AM.

[xrocketengineer]

Besides what FS is suggesting, there is another long shot possibility. I don't know the configuration of the compressor electromagnetic clutch for the Mini but with General Motors clutches, unusual wear on the clutch causes problems. A friend of mine and I had issues with the clutch randomly disengaging and re-engaging after running for a while. It turned out that the driven plate on the clutch had concentric wear grooves instead of being flat. This was caused by slippage between the driven plate and the driving pulley when engaging the clutch. The pulley had concentric slots that caused the wear on the driven plate. Apparently, the grooves would affect the magnetic field of the clutch causing the erratic behaviour. The more often the clutch engages/disengages the more the wear.

I fixed my plate by making it flat again with a flat file. I don't remember if my friend replaced the plate or if he used the flat file method. I had the same issue and clutch wear pattern with a Craftsman lawn tractor with an electric clutch (identical to the GM ones), however, I did not know at the time about the wear causing the problem and ended up replacing the clutch assembly.  

[bluedragon]

On most A/C systems, if the relay is suspected of being the problem with erratic compressor cycling - this can usually be verified by putting a jumper between the relay pins, thus bypassing the relay and keeping it energized at all times. If this works, then it *could* be a bad relay and is worth chasing a replacement.

 

I doubt the relay has any special properties other than being a plug-in fit, so if worst came to worst, I'm sure a competent A/C company could adapt another relay to work.

 

But there could be reasons a working relay would not energize the system. The most common is if too much refrigerant has been pushed into system (most commonly a result of a novice quick fix for a A/C problem - just shoot a can or two into the system without actually knowing how much is already in it.) These causes pressures to rise much too rapidly in operation and trigger the overpressure switch, which then could result in the relay being signalled to cut out. (not sure if the Mini system is set up this way, some have the switch and relay all as one.)

 

If the system runs a short time then cuts out, I'd lean towards overpressure or a worn compressor clutch as described above over a relay problem.

[Gary33031]

After searching the engine bay, I finally used a mirror and light under the dash and I found my AC relay unit. That's the good news, bad news I have no idea how to remove it for testing. It's black and looks just like the injection relay under the hood. I located the relay on the dash rail adjacent to the boot latch pull. I'll take the car to my Mini Tech and see if he can remove the relay and test it. Once it's out, maybe we will actually find a part number on it.

[FlyingScot]

Has it worked since you had the car? The reason I ask is that most folks I know or have commented on these have said they are white....and my own one is. I am going to an event this weekend where there will be a number of JDM cars so I'll check those.
Just a niggle that maybe someone already tried an engine MFU....

Let us know your findings, as some information isn't fully documented.

FS

[Gary33031]

Has it worked since you had the car? The reason I ask is that most folks I know or have commented on these have said they are white....and my own one is. I am going to an event this weekend where there will be a number of JDM cars so I'll check those.
Just a niggle that maybe someone already tried an engine MFU....

Let us know your findings, as some information isn't fully documented.

FS

Has it worked since you had the car? The reason I ask is that most folks I know or have commented on these have said they are white....and my own one is. I am going to an event this weekend where there will be a number of JDM cars so I'll check those.Just a niggle that maybe someone already tried an engine MFU....Let us know your findings, as some information isn't fully documented.FS

Yes, system works very well and blows cold when the clutch engages. Don't know if I need a new AC a Compressor and clutch or a relay. "Flying Scot", from Scotland? My ancestors are from Scotland, last name MacDonald. Let me know f you get any useful information at the event your going to. Thanks, Gary.