Hybrid mode doesn't engage after warming up

Hear loud fan noise from rear sometimes, not others

Hear loud fan noise from front sometimes, not others

Just changed my MECS pump at the dealer to the brushless one

Ac blows pretty cold

Is it the hybrid cooking fans that are bad? The blend door reading is 0000DTC so I don't think it's that.
What other x gauges would be useful for diagnosing?

Thank you!!

 

I had a similar problem with my '06 about a year ago. It was the hybrid cooling fans. About $250 and 2-3 hours of work did the trick. There's a good write-up on DIY fan replacement on edmunds.com that's linked to from a post in this forum.

Note that I had preemptively replaced the blend door actuator shortly after acquiring the vehicle in 2012, at the same time I did the MECS pump.

 

You could double-check the temperature reading by feeling the top of the hybrid battery when it should be fully operational. At 100F it will be hot, but not too hot to put your hand on it briefly. As you probably know if the battery reaches 100F the regen system won't work.

Since the cabin a/c is good, you at least know the portions of the a/c system that are shared must be ok.

If the battery is not being cooled, the problem can be other than the fan or the blend door actuator. The rear hvac unit may not be getting refrigerant. The control system that decides whether to send refrigerant to the rear hvac unit may malfunction. The valve that the control system orders to open or close to allow refrigerant to flow through the lines to the back end may malfunction. The lines may be blocked. The paper filter may be clogged. The side window vent may be plugged.

 

That's an excellent point. Easy to check and cheap to replace.

 

Unlikely, at those temperature the blend door will be closed if it is working properly and the a/c will be on. The filter is before the blend door in the flow of air.

 

After its run for a while and it's heated up crawl under the back and feel the AC lines back there. If one line is not cold then there is probably a problem in the AC system like Xspirit said.

 

It is possible the switch for the rear a/c is disconnected or bad. There is an x-gauge for ac on these trucks, what you could do is make sure that the a/c is coming on even when the front isn't asking for it (from a/c or defrost) if that all seems ok an easy way to check that the ac is coming on in the back properly is to disconnect the ac plenum crossover from the plenum to the battery, there are a few 8mm bolts and one scrivet, plus you have to take a side interior cover off I believe, they just pry off around the edges. Check and see if you have cold air inside of there.

Another thing to make sure of is that if the a/c should be on (outside temps above 70s I believe or for sure mid 80s then the blend door will be shut. Take out the air filter and look down right below it, if it's up it will be the thing that's slightly springy, DO NOT force it down, it has a worm drive and you WILL snap something, most likely the door itself which will be about the most unfun thing ever to change out.