fluctuating AC

I recently purchased an 05 LGT MT Wagon and with the AC on 65 (both pass and driver) you can feel the AC go super cold (like it should on 65) then go warm, then cold, then warm.

 

It will do this with no correlation to speed or outside temperature, and it can do this a few times in a five minute span just to give you an idea.

 

I've read a lot of posts regarding the AC and the finicky dual zone temp set-up but I haven't read anything like what I'm experiencing.

 

I also had the AC system flushed and charged just the other day to see if that helped. There were no leaks found and temp still fluctuates as it initially did.

 

I did read a thread in here that linked to a long term review of the LGT Wagon and it talked about the same problem that the dealer finally solved to be IIRC some type of AC relay or something of the sort........ I've searched again on this forum and have not been able to find that thread either....any help is greatly appreciated.

Is this in the auto setting or manual ?

 

In the 5 years I've owned my 05, I have used the auto mode about 3 times. I hate it.

I'm pretty sure this is happening in the auto mode.

 

Update:

 

I found my passenger footwell soaked with water from the AC (I've only owned the car for a few days and it took 2 weeks to get shipped to me in Hawaii). Quick research on this forum made me suspect a clogged drain hose.

 

Unclogged drain plug, dried out car today...AC seems to run a little better but still fluctuates.

If it is in the Auto mode, it will fluctuate. It is just like your home a/c heating system. It has to maintain a specific temp and at times it has to add warm air to the cold air to maintain the set temp.

True and I know that. I hear AC in businesses go on and off all the time. My family owns exclusively Lexus' and Infinity's and I can tell you that on those cars on Auto mode temperature does not go that warm like it does in my car to stabilize 65 degrees LOL

True and I know that. I hear AC in businesses go on and off all the time. My family owns exclusively Lexus' and Infinity's and I can tell you that on those cars on Auto mode temperature does not go that warm like it does in my car to stabilize 65 degrees LOL

Well for one you do not own a Lexus or Infinity, so that idea is moot. You own a Subaru.

 

Second what is the outside temp when you have it set for 65 degrees? I can tell you if it is cooler outside, then it will blow warm inside to achieve 65 degrees. Then again, I wonder if it could be the thermistor, who knows.

 

Third, take it in to be looked at then. Talking about it over the internet is doing nothing to fix it.

Well for one you do not own a Lexus or Infinity, so that idea is moot. You own a Subaru.

 

Second what is the outside temp when you have it set for 65 degrees? I can tell you if it is cooler outside, then it will blow warm inside to achieve 65 degrees. Then again, I wonder if it could be the thermistor, who knows.

 

Third, take it in to be looked at then. Talking about it over the internet is doing nothing to fix it.

 

First point well taken I've come to realize reading previous posts on here about the AC, just never thought it was so bad.

 

Second point, I'm in Hawaii so outside temp is usually 80+ degrees almost year round.

 

Third, I can take it back in, but what I'd like to know if this is or isn't characteristic of the GT system that's what I'd like to determine. Talking about it over the internet with those who know these cars well is what I'm trying to do.

 

I've seen a lot of good posts on this site with really great answers and solutions that may otherwise take a lot of time and trips to a mechanic whom may not be familiar with Subaru's.

 

You gotta realize to get this car I had to buy it on the Mainland then ship it here. You can be on the road here (and its and island) for a whole month if not longer and you won't see one.

 

So any help on here I can relay to my mechanic to send him in the right direction would be great. Last resort I'll go to the dealer but trying to avoid it as much as possible.

 

In the 5 years I've owned my 05, I have used the auto mode about 3 times. I hate it.

 

 

HINT, do not use the auto mode. After I had my car a few weeks, I went back the dealer and told them how bad the auto mode was.

 

It's the one thing I hate about the car. The thing is useless. Just don't bother with it.

+1.

Thanks for the tip. The AC still fluctuates on manual and the AC system was flushed then recharged so it can't be that either. So I guess that's just how it is. The LGT MT Limited wagon is still an awesome car regardless.

Let's assume it's 80+ outside and sunny.

 

Set it to auto and set the temp at something sensible, like 75. Then let it do it's thing. I bet you notice it works better.

that's interesting. I'll give it a shot and post the results.

Let's assume it's 80+ outside and sunny.

 

Set it to auto and set the temp at something sensible, like 75. Then let it do it's thing. I bet you notice it works better.

 

Ok had to go do an errand and temp on car said it was 87 degrees outside. Set the AC to AUTO 75 degrees both zones. I must say this worked pretty well. Temp seems to fluctate less and having heat rejection tint (the tint actually blocks out 80% of the heat not light) tint all around including the windshield (70% on the windshield you can't even tell it's tinted) 75 is not bad at all.

 

I'm gonna run around with it like this and see how it works over a range of inside and outside temps. Although it always pretty much 80-90 degrees here in Hawaii.......

Ready for the explanation?

Ready for the explanation?

 

Geez.

 

Anyway an update. It was 71 degrees showing on the car temp gauge. Still had the AC set on 73 degrees MANUAL from driving during the day when it was 87 degrees. This did not work well at all. I dropped the setting to 67 degrees and this seemed to work better.

 

So it seems that setting the temperature on MANUAL will work and blow somewhat constantly cold provided the set temperature is quite lower than what the car is reading for the outside temperature.

Leave it in auto and just let it do it's thing.

Even in full manual mode set to 65, the compressor will cycle on and off. Its not like other cars where it will keep the compressor on if there is a call for constant cold or the MAX a/c setting like in older GM vehicles. I dont care for it cycling either. If I want cold, I want COLD!

it turns off because the coil gets too cold. then there is a minimum off time before it comes on again. That's why it goes hot cold so fast. That's why setting it to something sensible like 75 when it's really hot works better. The coil sees a larger heat load and doesn't get so cold so quick that the compressor cycles off due to freeze protection.

it turns off because the coil gets too cold. then there is a minimum off time before it comes on again. That's why it goes hot cold so fast. That's why setting it to something sensible like 75 when it's really hot works better. The coil sees a larger heat load and doesn't get so cold so quick that the compressor cycles off due to freeze protection.

 

 

There's got to be a way around this?!!! I'd do without the outside temp sensor in a heartbeat if it had anything to do with it..

it doesn't!

The AC sucks in these cars and can't keep up with brutal summer temps here in the Midwest. The A/C compressor cycles to prevent it from freezing up and that is why you keep feeling it go between cold and warm. Stupid design, it should have a temp sensor so that it can stay on longer when it is hot out instead of just cycling constantly. I am planning on getting window tint to help it out as on hot sunny days it can barely keep the cabin comfortable even with recirc turned on.

 

P.S. I have a 2.5i with the manual controls and it behaves this way.

Imagine its basically summer temps all year round here, and humidity high but prolly not as high as the Midwest at its best.....

 

What about a larger compressor, it is very small........

FYI, I use auto all the time. It is hot as shit here in FL (the worst I have ever experienced) and Auto keeps my car chilly! never had any issues with it getting warm. Glad you got it sorted.

My a/c cycles every 15 sec from warm to super cold. It doesn't have any correlation to outside temp, RPM, throttle, e tc. It is quite noticeable with high humidity as you can feel the moist air. Dealer can not replicate the problem.

My a/c cycles every 15 sec from warm to super cold. It doesn't have any correlation to outside temp, RPM, throttle, e tc. It is quite noticeable with high humidity as you can feel the moist air. Dealer can not replicate the problem.

 

Pretty much the same scenario here.