Hello everyone,

I have been having an odd issue with my climate control system.

It all started after picking up my car from the shop after a stakedown kit installation.

I started noticing if I set the speed knob to Low, the fans will not turn on at all, though the compressor is engaged and I notice the RPM drop. It will work okay if I set it to Auto or High.

Yesterday, the entire system stopped working for a while. I could not turn it on and, when switching temps between 65 and 85, the servos did not move and the blowers never engaged.

After driving for a while, I played with the speed knob turning it off and on and it engaged again, moving all the servos when switching temp. Low was still not functional but Auto and High worked just fine.

If I leave it on Auto, the blowers will work in different speeds, including Low.

I am not very proficient to troubleshooting these so I don’t know where to start. I inspected the 50A fuse and it seemed okay.

Any advice on where to start is appreciated.

PS: I have replaced the climate control module with one from Jag Aire about a year ago.

 

The problem with your low fan speed might be the fan relay (actually, four relays in one casing) behind the console's left side cheek panel. Check connections carefully; they're sometime dirty, loose, or overheated. Or, the relay may have failed.

As for the entire system sometimes being inoperative, intermittently, I would suspect a dirty fuse or poor connection. I'd begin by removing all four of the climate control fuses cleaning the contacts/clips, and cleaning the fuse end caps. I bit of corrosion can cause problems.

If no joy, we can dig deeper

Cheers
DD

 

I suppose it is a good idea to disconnect the battery then? If so, the right order is disconnecting the negative, then the positive, correct?

 

To be absolutely safe and sure, yes, disconnect the battery.

No need to disconnect both cables in this case. Disconnecting just one will do the trick. Make it the negative.

In cases where both cables need to be removed (such as replacing the battery) I disconnect the negative first, then the positive. On reconnecting, positive first then the negative.

Cheers
DD

 

So I removed that big relay and disconnected all the cables. They seem okay. I found some corrosion at the base of one of the tabs on the relay but nothing major that could be covering anything. I also removed the black cover and looked for anything that could be broken but it seems okay, though I found a very little piece of metal just loose in there.

Today it seems to be just the Low setting that is not working as expected. The rest is working, including the servos.

What could I try to check next?

 

what to check next:

in the passenger side footwell, up in the firewall, right corner, almost invisible hidden by the blower case, there is a small sensing circuit board that I think senses incoming air temperature. You will need a bright light to find it.

this circuit board gets covered with greasy grime through many open-close cycles of the blower case flaps.

unscrew it and use a soft toothbrush to clean the grime off of the electronic resistor and other parts.

see if that causes any change. In my car it did after I cleaned it. The system came alive with energy.

 

Hey Jose.

Took me a while to get to what you described. I believe I found it but it was perfectly clean. I still made sure the connections were sturdy.

Since the day I posted, every other speed worked okay except for the low speed. Whenever I try to turn the blowers on low, I hear clicking as it engaged whatever electrical part needs to be engaged but no blower motion.

I will attach a picture of the circuit board, just to make sure it is what you meant.

 

sorry for the trouble you went through but that one seems to be attached to the blower case and it is not the one.

is your car Left Hand Drive or Right Hand Drive?

if LHD, it will be on the front passenger side, towards the kick panel, away from the transmission tunnel, screwed to the firewall itself and the wires will be soldered to it, no spade terminals as in your photo.

to see it, you need a bright light, push the front seat as far back as possible, and you need to lay on your back resting your head on the rise towards the firewall, then looking up and to the left. It is a small rectangular board.

you don't need to remove it, only to clean it with a toothbrush or vacuum cleaner brush.

if the car is RHD, then the opposite directions should be true.

I believe the best troubleshooting will be to substitute the large relay and see if the blowers work in LOW speed. Cleaning that small circuit board will not necessarily fix the low speed issue.

 

Oh, okay. I will look better the next time. I did have a total “failure” so it’s probably a good idea to check that board.

What relay would that be? I’m sorry, I’m not very clever when it comes to those. LOL

 

the large 4 relays relay.

that relay controls the 4 speeds of the blower fans. The one you opened and inspected.

 

Ohhh. I’m sorry.

I might as well do that. It looks older anyway, and the little piece of whatever I found inside it just hanging doesn’t sound right.
I’ll look into purchasing a new one and will report back!

 

it does sound like it is the cause.

 

These are pictures of mine when I had it apart. I think this is the 4 relay pack you are talking about, right Jose?

Dave

 

yes Dave, on the first picture it is the large relay on the right.
here's another illustration:

 

Just wanted to give you guys an update.

I replaced the big air conditioner relay and voila, Low now works. Ordered it from Everyday XJ and David Boger sent it fast!

Thank you so much for all the help.