Is my AC cold enough?

[Yah-Tah-Hey]

Your temps seem fine to me- a 50 degree differential while driving and slightly under that while stopped I would consider fantastic.

Exactly how cold do you want the car to be? Is 45 degrees coming from the vents not comfortable? Understand that when stopped, your AC performance will drop some, that's normal. I question the accuracy of the measuring instrument used by anyone reporting temps in the 30's when it's 90+ degrees out.

I think the issue might come down to expectations. Maybe time to tint some windows?

I would invest in some gauges and you will get a much better idea whether the system is performing normally.

Well the evaporator temperature is maintained at 34/36F on many vehicles to prevent frosting/icing. With you there, anyone that says their AC is freezing cold is BSing.

 

[demarpaint]

It is if ambient is 100F. Any AC system that can provide 55F at the vent is doing a spectacular job.

I beg to differ. I recall seeing about 48F-50F in 100 degree weather from my E-150. I know of plenty of vehicles doing better than that.

 

[92saturnsl2]

It is if ambient is 100F. Any AC system that can provide 55F at the vent is doing a spectacular job.

That's what I'm thinking. I'll have to test mine, but I'd be surprised if they were under 50 at idle, when ambient temps are well into the 90's.

 

[Snowflake White]

That's what I'm thinking. I'll have to test mine, but I'd be surprised if they were under 50 at idle, when ambient temps are well into the 90's.

Not from my experience, I've seen plenty of cars with temps in the low 40s when the temps rise to near 100, but still in the
low 40s (41-43) in mid 90s with relative ease.

 

[PWMDMD]

The temp drops about 2-3 degrees while driving. Also, my thermometer reads about 50 with the fan on high. I've read that's normal for the temp to decrease with more air flow.

If you're talking about the airflow over the evaporator then it's the opposite...the faster the airflow over the evaporator the less time there is to cool the air.

 

[Jonas]

If you're talking about the airflow over the evaporator then it's the opposite...the faster the airflow over the evaporator the less time there is to cool the air.

Interesting. My two middle vents are about 3 degrees cooler than the ones by the windows.

 

[Jonas]

All I know is I'm sweating when it's above 90, sun is out, stuck in traffic. The temperature climbs more and faster when I'm stopped in drive, than when I'm parked. I was cozy for my shift tonight-even though it was in the low 90's, it was cloudy and there wasn't too much traffic. It's like the AC shuts off when I come to a stop. Also, when I turn the car off for more than a few minutes in the sun, the vents will not get below 60 degrees until I start driving. Cabin temps are in the mid 80's when I'm delivering around noon. I don't think they could sell this car new to anyone in a hot climate with such a weak air conditioner.

 

[Jonas]

Not from my experience, I've seen plenty of cars with temps in the low 40s when the temps rise to near 100, but still in the
low 40s (41-43) in mid 90s with relative ease.

Mine gets down to about 44/45 on the interstate with the fan on medium high when it's hot outside. Do they stay that cool when stuck in traffic too?

 

[Jonas]

I also cleaned the condenser, which didn't make much if any difference. I also don't think my blend doors are letting in hot air because I drove about 15 minutes with the AC off and the vent temp stayed about 10 degrees cooler than outside. I'm leaning toward weak fan(s) since the temperature difference is so drastic between driving and stopped in traffic.

 

[wtd]

I just cleaned the condenser with Web Coil Cleaner I got from Home Depot. As I was rinsing it with the hose, I could eventually see water going through the fins and out the fan side, so it seems clean(er) now. I will check the plastic dams, I'm not sure. I charged with cans using a scale. I tared the scale with can attached and did the math. I weighed the can's afterward to double check and together they lost exactly 16.09 oz.

Did you also clean the radiator? The fans pull air through both.

The only problem with charging with cans on a scale is you have to account for the extra weight the charging hose adds to the scale. If you did that then you should be close.

 

[wtd]

At this point a set of gauges would be helpful; pressure readings should point you in the right direction instead of just guessing.

A poorly performing condenser would manifest as a high reading on the high pressure side.

There's tons of info online how to interpret gauge readings, this is one example.

I had a mechanic botch an AC job not too long ago (overfilled system), that was all it took for me to pony up the money on the tools to do it myself. Buying a vacuum pump and set of gauges was some of the best money I've ever spent, both can be had for under $200 at Harbor Freight. Saves having to rent one every time you need it, and I just don't trust a rented vacuum pump. I called around and found a place that would evacuate refrigerant for $20 as long as I called ahead of time and they weren't busy. I won't give you too much grief for exhausting it into the air as I'm sure many of us have done it in a pickle, but you should be able to find someone that will do it inexpensively.

I got my own AC tools years ago after checking into how much it would cost to replace the compressor and related components and recharge the air in the 92 Cavalier that my fiancé was driving. She bought me the tools and I went online and learned how to use them and the correct procedures on fixing and recharging the systems. This was in 2006 and since then I have probably fixed 15-20 cars of our own and friends and family.

It was a great investment that has saved us tons of money over the years.

 

[Jonas]

Did you also clean the radiator? The fans pull air through both.

The only problem with charging with cans on a scale is you have to account for the extra weight the charging hose adds to the scale. If you did that then you should be close.

I suppose I cleaned the radiator too. When I sprayed the condenser with the hose from the front, water went all the way through it and came out the other side on to the fans. What I could see of the radiator looked perfect-light aluminum color, no bent fins. The condenser was somewhat dirty because it became a lighter color like the radiator after cleaning. I did account for the weight of the cans too. I tared the scale to 0 with the can on it so it showed negative however many oz going in. I also weighed the cans again after I was done to double check.

 

[Jonas]

I got my own AC tools years ago after checking into how much it would cost to replace the compressor and related components and recharge the air in the 92 Cavalier that my fiancé was driving. She bought me the tools and I went online and learned how to use them and the correct procedures on fixing and recharging the systems. This was in 2006 and since then I have probably fixed 15-20 cars of our own and friends and family.

It was a great investment that has saved us tons of money over the years.

Good call. I'm probably going to order at least a set of gauges tomorrow since I've already borrowed about 4 of them now haha.

 

[Jonas]

It's hard to say whether or not your fans are spinning as fast as they should be. My experience with fans are either they work or they don't.

You could still have a blend door issue where the door that directs air for the heat or the AC is not functioning correctly, is stuck, or can't close or open all of the way which means you could be getting a little bit of heater air instead of all AC air. With one vent not working correctly, it's possible you have other issues under the dash.

If you spray cold water on your condenser with the air on, does it affect your vent temps?

"If you spray cold water on your condenser with the air on, does it affect your vent temps?"
I did and the vent temp dropped dramatically-about 5-6 degrees in a few seconds.

 

[Jonas]

It's hard to say whether or not your fans are spinning as fast as they should be. My experience with fans are either they work or they don't.

You could still have a blend door issue where the door that directs air for the heat or the AC is not functioning correctly, is stuck, or can't close or open all of the way which means you could be getting a little bit of heater air instead of all AC air. With one vent not working correctly, it's possible you have other issues under the dash.

If you spray cold water on your condenser with the air on, does it affect your vent temps?

Yes, I sprayed the condenser and the vent temp dropped 5-6 degrees in a few seconds.

 

[Jonas]

Did you weigh the charge? If not you could be over or under charged. If you weighed the charge then you could have a bad expansion valve, a bad relay, blend door problem, plugged up condenser, fans not working properly, etc. It was suggested you run cold water over the condenser and check the temps, try that and report back.

I was discussing this very same issue this morning with my buddy @Trav. A friend of mine is $1,300 into a hack fixing his AC and it still isn't right. The smart money on my friend's AC issue is the relay..............

The water on the condenser made the vent temp drop 5-6 degrees in a few seconds.

 

[demarpaint]

Not from my experience, I've seen plenty of cars with temps in the low 40s when the temps rise to near 100, but still in the
low 40s (41-43) in mid 90s with relative ease.

As I mentioned earlier, there were vehicles doing better than my old R12 E-150, and now I know of another. My R1234YF refrigerant Wrangler beats my old van as does my R134 Liberty. I think with the case of the old E-150 the size of the cabin has a lot to do with it.

 

[PWMDMD]

Interesting. My two middle vents are about 3 degrees cooler than the ones by the windows.

Airflow over the coil/evaporator is important. If the air is moving too fast it does not have time to cool or dehumidify. If the air is moving too slowly and there is not enough warm air going over the coil then it freezes. I've never had a problem with freezing evaporators in a vehicle but I have had several vehicles where the air temp coming out of the vent was coldest on 2/3 max fan and once you turned the fan on high the temp of the air at the vent increased a few degrees. At that point, the fan is pushing air over the evaporator faster than it can cool the air.

 

[wtd]

Good call. I'm probably going to order at least a set of gauges tomorrow since I've already borrowed about 4 of them now haha.

I have several sets of Robinair gauges and like them a lot. I have one Snap on set I bought used as well.

 

[Jonas]

Airflow over the coil/evaporator is important. If the air is moving too fast it does not have time to cool or dehumidify. If the air is moving too slowly and there is not enough warm air going over the coil then it freezes. I've never had a problem with freezing evaporators in a vehicle but I have had several vehicles where the air temp coming out of the vent was coldest on 2/3 max fan and once you turned the fan on high the temp of the air at the vent increased a few degrees. At that point, the fan is pushing air over the evaporator faster than it can cool the air.

Interesting. My thermometer definitely reads coldest on low fan and goes up a bout 2 degrees with every click of the fan (4 settings)