A/C efficiency

[jseabolt]

I know it's been hotter than normal this summer (97F is hot where I live) but
I'm wondering if it's time to have the A/C on my Explorer serviced. Or the refrigerant replaced?

I don't think there is really anything wrong with the system but some guy I work told me that R 134a (or any refrigerant for that matter) looses it's efficiency after 15 years. Just like antifreeze would. That sounds logical but is that true?

If the system was low on refrigerant I would think the evaporator would ice over which it is not doing. Or can low refrigerant also lead to loss of efficiency?

This maybe comparing apples to oranges but on my '03 Subaru I checked the temperature of the air coming out of the vents on just A/C (not recirc mode) and it was around 33F and it was about 93F outside.. This was while using one of those temperature pens.

On my Explorer I was using an analog temperature probe stuck in the center vent it's was showing 45 to 50F around 97F outside.

The Subaru does in fact feel like it's cooling better than the Explorer. The only time I run my Subaru in recirc mode is if I get behind a diesel powered vehicle, a skunk that has sprayed or i'm driving past the sewage treatment plant or paper mill.

But on the Explorer I have been running it in recirc mode all the time. Which drops the temperature but creates awfull lot of noise. Of course it's going to feel colder in recirc mode because your cooling cold dry air rather than hot humid air which makes it feel colder.

So how cold should be air coming out of the vents actually be? 33F on my Subaru sounds like it's working to it's full potential because A/C systems should turn themselves off at 32F to avoid icing over the evaporator based on what I've read.

That same guy who told me refrigerent get's "old" is going to let me borrow some tool he bought at Autozone you hook to the low pressure side and after it cycles tells you if the system is working properly. He says he was able to use it to troubleshoot a plugged orfice tube on his Chevy truck.

Also what I don't understand is why the Explorer's A/C system is backwards or appears to be backwards.

I traced the routing and the hose coming off the condensor goes into the bottom of the evaporator then there is a pipe coming off the top of the condensor goes into the dryer. Then from there the hose leads back to the compressor.

Shouldn't the hose coming off the condensor be going to the dryer then the evaporator rather than to the compressor?

 

[BobWiersema]

Refrigerant does not wear out or loose efficiency. Not possible, its just a chemical that gets compressed and expanded, not consumed. Sounds like you may be a little low on charge. The best way to properly charge a vehicle is by weight. So you would empty out the system, pump it down and charge it back to the factory weight. All the AutoZone gadgets in the world will not tell you if the system has the correct charge in it. You can get it close, in your case I would probably add about 6oz and see how it works. A temperature of around 45°f isnt bad but you can probably do a little better.

Bob

 

[David in NC]

Congrats to your Subaru! That's chilly.

 

[davidcd]

I've heard of "icing" in a/c systems ... & you mention "icing over the evaporator" ....

I'm having a problem with my Mountaineer's a/c : when I was driving today with the a/c on, the airflow started out well enough but, subsided down to barely coming out of the vents; I could hear the blower working but, very little air. When I got home, parked the car, and turned it off ... after sitting for about an hour, I noticed a lot of condensation drainage - and still dripping. When I started the car and cranked up the a/c, the air flow was back to normal. So, I'm guessing I'm having this "icing" problem and when the ice melts, I'm back to good operation until it ices again.

Is there a remedy? You mention low refrigerant might cause the evaporator to ice over. Can you point me to some shop manual information about this?

Thanx.