Intermittent air conditioning problems ….

[BlueTriton59]

Last week it was hot here in Brisbane.

Mid afternoon Thursday I did a 25 minute drive in my 2019 MR dual cab to a friend’s house and the AC worked as normal.

After an hour I went back to the car and started up, and the AC blew hot air eg same as outside air temp. Checked all the settings and they were normal. Opened the car windows to let the hot air out, made no difference. Turned the AC on and off a few times. Drove the 25 minutes back home and AC still blowing hot air - not even a hint of cooling.

I noticed that when it was blowing only hot air, the car was idling high at about 950 rpm and not doing the cycling up and down from 600 to 950 as Tritons normally do when the AC is turned on. It just stayed at the high idle.

That evening I did a short run to the shops and lo and behold it started blowing cold air…. For about 2 minutes, before there was a noticeable change and we went back to hot air again. Stopped at the shops for a few minutes, then same thing again - started off cool, then like someone switched it off, hot again.

Friday morning early I tow the boat 3kms to the ramp, launch the boat and park the car - and all the time its blowing nice and cool again! Go fishing for a few hours, come back, open all the windows, start the car, and cool air again. - but again after about 2- 3 minutes its like a switch turns off and its hot air again. Got home, popped the bonnet and couldn’t see any obviously frozen bits. Tried to see the compressor to see if we could see the gap when the clutch engages but couldnt see it.

Now to Sunday and beyond to now (Tuesday) - I have done several drives, up to 45 minutes, stopped and started etc, and ITS BACK TO WORKING NORMALLY AGAIN! Air seems to be as cool as would normally expect in this hot humid weather we have been having.

I had it booked in at the local dealer tomorrow (car is still covered by the 7 years warranty) but cancelled that earlier today because I figured that they wouldn’t be able to find anything since its now back to normal and they would then want to charge me the $165 “diagnostic fee” when they couldn’t find anything wrong….

By my limited AC knowledge if the gas was low/escaped then the AC would not get cold at all, or not stay cold as it has on the longer test drives I have done, so it’s something else…

Plan at the moment is just to monitor it and if it happens again, to try to go direct to the dealer so they can see the problem live in real time in front of them….

Mate who has a MQ says it sound’s similar to an issue he had a year or so ago that eventually got to the point where the AC didnt work at all, it was the clutch in the compressor and a new compressor solved his problem.

Any thoughts?

[BlueTriton59]

As at today the AC is still working perfectly. No further “hot air” conditions since.

My current theory is that it was an intermittent fault of the AC compressor relay. This seems to be a fairly common issue reported by others that causes similar issues as mine had. Its relay #9 in the workshop manual.

I have searched everywhere I can think of and even looked at the online manual, but for the life of me, I cant find a part number or specs for that relay.

I pulled it out to have a look, and also just to eliminate a dry contact, and its marked as made by Panasonic but no other markings that I can see on it. Its super small so maybe I need a magnifying glass for these old eyes!

I wouldn’t mind getting a spare one just in case this problem happens again. It cant be that “special “ of a relay, if I can get a part number Im sure I will be able to pick up a Narva or Bosch one at Repco etc.

Can anyone help with the correct part number or specs?

[BlueTriton59]

Never mind, found the tiny part number printed on the relay.

For ref its Mitsubishi part number 8627A030
$23 from Mitsi dealer. Not too bad.

Not readily available in other brands feom the likes of Repco, Suoercheap etc.

Have fitted it, will see how things go and report back if the problem recurs.