Climate control problem:

[bw10030]

Last weekend, I took my wife's Yeti (L&K diesel)on a long run (2 lots of 3 hour legs), and noticed a climate control issue.

 

After an hour or so, we noticed the interior of the car getting colder and colder. The car was at normal running temperature, and the inside temp was set to 21 degrees. Outside temperature was 13 when I set off, but dropped to around 8. The system would not put warm air into the inside, I fiddled with various settings, and eventually managed to get warm air into the car by turning the control up to 24 degrees on both sides. The car did not get hot, but became habitable again.

 

After 3 hours we stopped for a quick coffee, when we set off again the heater / climate worked fine - we had to turn the controls back down to 21. However after an hour or so the same thing happened.

 

So a trip to the dealers is coming up, but any ideas what may be the cause?

 

 

[Ryeman]

There is a thing called a TX valve.....usually buried near the firewall which can 'stick' and eventually fail......just a guess.

Google

https://en.m.wikipedia.org/wiki/Thermal_expansion_valve

[blobbs]

My car does this also. This is my third Yeti and they all seem to do it. I thought it was the way it worked. If your dealer can find anything wrong could you post it on here so I can see if my dealer will do likewise?

[jtdesign]

I have found the same effect, but discovered that if you keep the vents by the side windows open then operation is much better. The vents can be angled towards the windows to help demisting as well.

The best explanation I can find for this behaviour is that there are some air temp sensors in the air flow to these vents and, if closed, the sensors read a higher higher temp due to warmth behind the dashboard (presumably from the engine through the bulkhead). Keeping the vents open means the sensors will accurately monitor the air temp and keep the cabin at the right temperature.

 

John.

[Urrell]

There is a sunshine sensor (small bump) in front of the storage box on top of the dash could this have been in strong sun?
It uses this to compensate the climate control for solar gain.

[bw10030]

Hi - well, after an Easter's testing, I think there's a real problem. The issue only starts after an hour or so, and it doesn't seem to be affected by vent position or sunshine. I took the car out for a run, got it to normal temperature (21degrees, A/C on, Auto selected 'Dual' mode), and for a while the temperature was finely controlled. After I had confirmed the 'static temperature', I adjusted the driver side up a degree (to 22) - instant warm air. reset the temp to 21, did the same on passenger side, same result. Reset to 21 degrees, and gave the system a few minutes to settle down, then turned the drivers side to 20 degrees - instant cold air. Let this settle for a while, then turned it back up to 21 - no warm air, and the vents were continuing to blow cold air - indeed far more than the -1 degree decrease in temperature demanded. The only way to get the vents back to blowing 'warm' air was to set the temp to 24 degrees. Reset the temp to 21 once I had warm air and the system seemed to work OK.

 

On another trip (i.e. the engine had been off and the engine cooled), I repeated the 'lower by 1 degree test', same effect (a lot of cold air and the temperature inside getting very cold), again when the temperatures inside and engine had stabilised. This time I left it at 20, and the interior just kept getting colder and colder - even on the passenger side, after a while. Turned the whole system off with the climate control for a few minutes (didn't want to risk frostbite!) turned it back on, still the same result. Turned it up to 24, warm air again. So sounds like something is awry.

 

A visit to the dealer calls - I have a leak or more an audible drip - related to the sunroof which may be a dockyard job to fix, so they can look at it then. If I find an answer I will let you know via the forum.

[Frenchtone]

there is a thermocouple sensor in the distribution system behind the dash, this controls air mixing to achieve temp selection/distribution, I had a similar prob with my first sm, thermocouple replaced and the system worked flawlessly, the various baffles/gates were also eased/lubricated at the same time!

[Ryeman]

there is a thermocouple sensor in the distribution system behind the dash, this controls air mixing to achieve temp selection/distribution, I had a similar prob with my first sm, thermocouple replaced and the system worked flawlessly, the various baffles/gates were also eased/lubricated at the same time!

We used to refer to it as the TX valve and is usually buried just like the EGR valve is.

[Frenchtone]

ah ok!worldwide terminology probs!

[Ryeman]

ah ok!worldwide terminology probs!

Not sure, the young techs may have another word for it..........my 604 TX valve failed ~ 30 years ago.

[SuperbTWM]

ah ok!worldwide terminology probs!

A thermocouple or T/C is just a sensor, I presume the V/V he is on about is what is actuated as a result of the output from the climate control

[Frenchtone]

^ yes but that could be the origin of his prob!

[g6zru]

Not sure, the young techs may have another word for it..........my 604 TX valve failed ~ 30 years ago.

That explains a lot.

 

Fred

[CFB]

Hmm, mine intermittently works the other way round.

Temp set to 21 and normally works fine, but every now and then the heater just keeps pumping out hot air.

I've discovered that if I turn the climate off for a couple of minutes, then turn it back on, all works fine for the rest of the journey.

I can live with it till July, when my new one will hopefully arrive.

[Ryeman]

Almost like a valve freezes up ......possibly heat soak frees it in time ........interesting/frustrating.

[speedsport]

Hmm, mine intermittently works the other way round.

Temp set to 21 and normally works fine, but every now and then the heater just keeps pumping out hot air.

I've discovered that if I turn the climate off for a couple of minutes, then turn it back on, all works fine for the rest of the journey.

I can live with it till July, when my new one will hopefully arrive.

+1

Exactly what mine does periodically..... and I too will put up with it until my new one arrives - hopefully at the end of this month!