Radiator/AC turns off temporarily

[Scrub]

Hi guys,

New on the forum, just picked up a 2015 BRZ limited MT with a little over 3k miles on it.

I've noticed on 2 occasions that my radiator/AC has failed while the car is stopped. Both times the AC will begin to blow uncooled air and the engine temperature gage will rise slightly (though not all the way to red). After less than 5 minutes it looks like the radiator kicks back in and both AC and temperature return to normal. Interestingly, both times occurred at the same intersection where I rarely go on my normal commute and after I had been driving about 30 minutes to an hour. Other times when I have driven for this length of time or more nothing has happened.

Since my car is pretty new I'm thinking that my dealership will take care of this under warranty. I've already set up an appointment with them for next Saturday.

Just wondering if anyone has experienced this or knows what may be the problem. Should I be concerned driving the car next week prior to my appointment?

Thanks everyone and glad to join the community!

[Ultramaroon]

Sounds like an electrical issue. When you say it goes back to normal after five minutes, is that five minutes of driving, or do the fans ever kick in?

You'll be safe as long as you're moving. Watch that temp gauge like a hawk if you're stuck in traffic. Yes, straight to the dealer.


Welcome to the forum!

[strat61caster]

That sounds like a normal combination of 'climate control' and this car to me.

In my experience the engine runs hot, there isn't enough thermal insulation and without the AC on it will blow hot air at you even with the dial turned to cold on the 'dumb' controls in the FR-S while sitting still. Even at speed the air comes in noticeably warmer than what's outside. In order to save fuel the car only runs the AC pump intermittently, with it cranked to cold it will cycle on and off at a stoplight, if you back off it will cycle slower allowing for noticeable variations in temperature.

I assume you had it set to a reasonable temperature like 70-80 degrees, the internal sensors basically can't keep up with how quick it starts pulling in hot air through the engine bay before cycling the AC on again. Set the climate control to a lower temperature and it should cycle the AC more frequently keeping you cooler.

But that's all just pontification, I'll be impressed if the dealership does anything and doesn't fall back on "it's normal it's trying to save fuel, if you're hot turn down the temperature more".

[wparsons]

^^ if the rad fan is also shutting off and the coolant temp is rising it's hard to blame on "set the AC colder".

[justatroll]

The AC dumps heat into the engine via the radiator.


If the engine is detecting that it is near overheating, it might be smart enough to turn off the AC via the AC Pump solenoid clutch.


Get the engine nice & hot and turn on the AC.
Then open the hood and watch the AC pulley, you will see it stop spinning as the AC engages/disengages.

[Scrub]

Thanks everybody for your replies!

I know the AC pulley starts and stops intermittently with the click sound. I believe this is a different issue since the temperature gage on the dash doesn't generally rise when the AC pulley cycles.

In any case I've moved my appointment to this Saturday. Have to sit through rush hour in an hour or so though wish me luck!

I will update with what the dealership finds is the root cause if anyone is interested.

[humfrz]

Originally Posted by Scrub

Thanks everybody for your replies!

I know the AC pulley starts and stops intermittently with the click sound. I believe this is a different issue since the temperature gage on the dash doesn't generally rise when the AC pulley cycles.

In any case I've moved my appointment to this Saturday. Have to sit through rush hour in an hour or so though wish me luck!

I will update with what the dealership finds is the root cause if anyone is interested.

Yes, we are interested in the dealerships findings.

There are relatively inexpensive instruments and apps that can monitor your car's water temperature, if you are interested.

Let's hope it gets sorted out.


humfrz

[billwot]

Originally Posted by Scrub

Hi guys,

...while the car is stopped. ... the AC will begin to blow uncooled air and the engine temperature gage will rise slightly

There is nothing wrong with your car. For the radiator and the A/C (condensor) shed heat, both require airflow. When the car is stopped, you only have minimum airflow, if any. When the coolant temp rises to a setpoint, the aux fans will turn on. That's why your temps will start to come back down after a few minutes. Don't worry, its normal.

[Ultramaroon]

Originally Posted by Scrub

Thanks everybody for your replies!

I know the AC pulley starts and stops intermittently with the click sound. I believe this is a different issue since the temperature gage on the dash doesn't generally rise when the AC pulley cycles.

In any case I've moved my appointment to this Saturday. Have to sit through rush hour in an hour or so though wish me luck!

I will update with what the dealership finds is the root cause if anyone is interested.

Yes, the compressor will start and stop but it won't help if cold air isn't being drawn through the condenser. Pop the hood and see if at least one of the fans is running when your AC is turned on.

Small changes in coolant temp are not reflected by the instrument gauge. It has a dead spot to keep people from freaking out over normal fluctuation. If you see that thing go above normal, something's wrong. Again, I think neither of your fans are kicking in.

[Scrub]

Originally Posted by billwot

There is nothing wrong with your car. For the radiator and the A/C (condensor) shed heat, both require airflow. When the car is stopped, you only have minimum airflow, if any. When the coolant temp rises to a setpoint, the aux fans will turn on. That's why your temps will start to come back down after a few minutes. Don't worry, its normal.

Thanks for your feedback!

Not to disagree with you or anything (I obviously know very little about any of this), but if that is the case, why has it only occurred twice when the car is driven daily and roughly under the same conditions/duration? Could it have anything to do with location?

BTW I sat through rush hour for about an hour today bypassing that cursed spot and my BRZ showed now signs of anything out of the ordinary.

I'll most likely swing by the dealership this weekend anyways since I've already booked and they've set me up with a loaner haha. At the very least it'll be some relief for me.

[Scrub]

Hi guys. An update - happened twice to me today. Second time I pulled over and popped the hood. I noticed that the AC compressor had stopped spinning and did not start up again until I had restarted the car (waited about 5 min).

[Ultramaroon]

Originally Posted by Scrub

Hi guys. An update - happened twice to me today. Second time I pulled over and popped the hood. I noticed that the AC compressor had stopped spinning and did not start up again until I had restarted the car (waited about 5 min).

fans?

[Sportsguy83]

Originally Posted by billwot

There is nothing wrong with your car. For the radiator and the A/C (condensor) shed heat, both require airflow. When the car is stopped, you only have minimum airflow, if any. When the coolant temp rises to a setpoint, the aux fans will turn on. That's why your temps will start to come back down after a few minutes. Don't worry, its normal.

A/C blowing hotter air from time to time, etc.. normal.

Temp gauge rising, not normal. It shows signs of a failing fan or other potential issue like low on coolant.

[extrashaky]

Originally Posted by Ultramaroon

Small changes in coolant temp are not reflected by the instrument gauge. It has a dead spot to keep people from freaking out over normal fluctuation. If you see that thing go above normal, something's wrong. Again, I think neither of your fans are kicking in.

This is a good point. That dead spot is at least 40° F wide. If it's moving above the middle detent position, the coolant temp has to be getting well above 220° F.

OP, if the aux fan is coming on, you should hear it. It sounds like a train in the distance.

Heat soak when coming to a stop after a highway run... I'm not that familiar with how boxer engines manifest symptoms, but in other vehicles I've had, that sounds an awful lot like early signs of a head gasket problem.

Stupid question: Have you checked your coolant level?