Air conditioning won't work when in 4HI?

I've got a bit of an oddball issue. I was doing my monthly drive in 4HI (as directed by the owner's manual) and had the AC going. Once 4WD engaged, the amber AC indicator started blinking and the air coming out of the vents got noticeably warmer. Not hot, just not as cold as it was when in 2WD. When I switched from 4WD back to 2WD, AC function resumed as normal.

Is this to be expected, or is it something I should bring to the dealership's attention? I bought my truck in certified condition, so I'm still covered by the 12 month bumper-to-bumper warranty.

 

Still covered? Yes, let them know. Make sure they'll fix it, cause they'll have no problem taking your money to fix anything in the future.

 

Is this the case every time you shift into 4Hi? Or was this a one time thing?

The two systems are not linked together so one should not have any effect on the other.

 

No it's not normal and it sort of sounds like your AC compressor is failing, the compressor RPM pick up sensor is bad, or your relay is sticking.

Your dealer should have more info on this when you take it in.

 

I read your post, so I decided to go test this on my truck as I have just bought this truck new Jan 31st. Started the truck. Put the AC on. Put it in 4HI. AC was fine. Took it out of 4HI and drove down the road with the AC on and put it back in 4HI. No problems. Continued to drive down the road switching it in and out of 4HI with the AC on. No problems.

Hope this test helps.

 

I'm going to test it again today. If the issue isn't repeatable in cooler weather, that would be good to know. It's around 80 degrees today, versus 95 degrees when I noticed the issue.

Thanks for the pointers.

That does help, thank you.

My concern here isn't a loss of functionality, since I rarely use the AC in the first place. I'm more worried about this issue being a sign of impending parts failure. I'll be sure to update this thread with the results of my test later today.

 

So I tried to replicate the issue today. I was (thankfully?) unable to do so. The ambient temperature was 82 degrees at the time of the test, which is lower than when I first noticed the issue (95 degrees). Does anyone have any idea what might be causing this to happen?

 

Imo. It was coincidence. I’d keep trying to duplicate not in 4hi.

 

Yeah, that sounds like a plan. July is gonna be here soon, so 100+ degree days will be plentiful. That should make testing easy.

 

The 4x4 system is actually separate from all else, it's very low tech and 100% did not affect the air conditioning.

 

It wouldn't hurt to check your cab air filter. Restricted airflow through the evaporator can cause way more A/C issues than 4wd.

 

I'd bet that the high ambient temperature caused the issue. I'll be doing more testing as summer weather starts in earnest.

The cabin air filter has only been installed since December, or 9000 miles. That said, I'll take a look to make sure nothing is blocking it.

 

If so, you need to make sure your radiator and condenser are clean, and that your fan clutch is working properly.

 

You think that's covered under the bumper-to-bumper warranty?

 

I doubt the cleaning is, but the clutch should be.

 

I just did a quick search for any related A/C issues, and found this. Perhaps it may be helpful. It’s an old thread, but after reading through most of the posting seems like a known issue with some 2nd Gens. And if it is fuse related at least it’s easy and quick to check/remedy. Here it is:

https://www.tacomaworld.com/threads/a-c-light-blinking.107982/

 

@Plucky was his name, great find! I’ll give it a thorough read later today.

 

Yes, Sir!