How does your new Subaru's AC work?


Asked by Aug 21, 2015 at 09:42 PM about the 2015 Subaru Forester 2.5i Premium

Question type: Maintenance & Repair

My AC works fine on flat ground but when climbing hills it blows put hot air instead of
cold. Even accelerating on flat ground causes the air temperature to rise immediately.  
The more throttle you give it, the worse it gets.  Backing off on the gas causes the air
coming out of the vents to become cold again instantly.

This seems to be an engine vacuum related issue but so far my dealer has no answers.

25 Answers


Sounds like the A.C condenser coil is partially clogged with dirt and bugs. Sitting idling does not need much air flow but driving air flow is restricted. Clean coil and radiator with a garden hose and nozzle or better yet a pressure washer that will remove the dirt and bugs to get better air flow across the fins of the coil.


It is a brand new car and everything is clean. If there was poor air flow through the coil it would be worse at low speeds, not at higher speeds. A pressure washer is a bad idea because you might damage the AC coil.


My 2003 Subaru with 200,000 miles is a far superior car to my 2015 in nearly every way and the AC works like a Cadillac's!

2 people found this helpful.

Never would have recommended it if have not used pressure washer myself just use the fan spray tip not the full stream tip.

1 people found this helpful.

The only other thing is the in line filter on the high side line of the A/C system is partially clogged or the blend door is closing off between evaporator and heater core for some strange reason.


There is likely a defective vacuum hose that goes to the heater and air controls inside the vehicle. Inspect all the vacuum hoses for cracks and splits. When going up a hill the throttle is open more and the engine makes less vacuum. I suspect a blend door or something similar is moving due to lack of vacuum and redirecting the interior air flow. Also NEVER use a high pressure washer on the a/c condenser or radiator. The high pressure water can collapse the cooling fins and ruin these parts.


Hey Bob let me ask you a question have you tried a pressure washing or are you just thinking that would happen ? I am a person that is not afraid to think outside the box. Tried it and it works great.


I have actually collapsed cooling fins on a radiator. If you get too close the high pressure will flatten them immediately. Even a commercial car wash pressure wand will do this if the wand is held too close. If you are very careful and keep your distance a pressure washer can be used, but one of these things in the hands of the inexperienced will do damage. I actually have a 5 HP electric pressure washer here at the house. It blew some of the factory paint off of a mirror on my 2003 Mercury.

1 people found this helpful.

Firebird, re-read the OPs question. I think you might agree that he has a vacuum issue, "Backing off on the gas causes the air coming out of the vents to become cold again instantly" is the key to this. The word "instantly"! Likely a vacuum reservoir that has a hole in it or a bad vacuum hose that controls the HVAC.

1 people found this helpful.

I have this very same machine.


You are right Bob I agree as I said in one of my previous answers that the blend doors cable might have come off or a vacuum like you said depending on what kind of system that operates the blend door.


And as far as the pressure washer is concerned do not hold it that close and use the fan spray nozzle not the jet spray that nozzle will bend the fins if you hold it to close or even far away.


The problem is fairly obvious but my question is - is anyone else having this issue with their new Subaru? My dealer is trying to make it sound like this is somehow normal as they do with all problems.


The AC on the new subarus sucks. I have a 13 XV and on a hot day its a pretty miserable ride. Our 2nd car is a 2002 Focus and it has ice cold ac. We run the Focus ac on the lowest setting and the XV's on its highest.

3 people found this helpful.

The PCM disengages the compressor clutch at or near WOT for better acceleration. So at such times the air won't be cold, but it shouldn't be hot either.

2 people found this helpful.

The AC on my new 2016 Forester also sucks. I actually got the dealer to replace the whole unit and it made no difference. I have the same issue with it switching to warm air for no apparent reason.

4 people found this helpful.

I have 2015 Forest. Same issue. I am in South Texas. In summer, it is a pain to drive it, AC just not strong enough. Just like being mentioned above, it does blow hit air when accelerating in high way or local at the first 20 minutes. I took it to dealer, they said it is normal.

1 people found this helpful.

Summer has been brutal here in FL this year. The ac in this XV Crosstrek is TOTALLY worthless. Keeps on using oil, as well. Had this thing since 13', and its been the crappiest car I've ever purchased.

1 people found this helpful.

Went to another dealer and they told me that the Forester has a very small refrigerant capacity which makes it difficult to get a correct charge. Too easy to be low or high. They double checked the refrigerant charge and it has worked just fine ever since.

2 people found this helpful.

Mine has now crapped out. Tomorrow I will try to recharge it.

1 people found this helpful.

Hi Iwas a suby tech at a dealer for years. They have programmed the computer to release the A/C clutch (turn off A/C) anytime the engine is heavily loaded: ie, passing, going up hill fast, or simply accelerating hard on flat ground. As soon as throttle position is returned to normal, Compressor clutch is reengaged and A/C gets cold again. Sounds like you are experiencing a normally functioning system. By the way, vacuum hoses aren't used to switch A/C doors or valves anymore, most all funcions requiring mechanical motion are handled with servo motors (mod motors) on automobiles these days.

4 people found this helpful.

Yes I know about the throttle thing. The problem was much worse than that but correcting the refrigerant charge did the trick. Since the AC system is marginal at best you have to run it in circulate most of the time. It now looks like the compressor is gone.

1 people found this helpful.

Just took mine to the dealer 2017 forester 12,000 miles a year old A/Condenser went bad they said major issue, many affected but no recall said 6-10 weeks to repair due to shortage of condensers for this problem// good thing it's October or I would have to trade it in because the wife would not go the summer with out A/C !!

4 people found this helpful.

I had to replace the evaporator, high side hose, all the O-rings and the compressor on my 15 Forester.

My a/c compressor just went on my 2017 Forester. I am very disappointed since its only 1.5yrs old! I was told it is on back order. Any idea how long this might take???? Not happy.

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