Is my AC cold enough?

[Jonas]

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.

I would love to have 45 degree air all the time. If I'm stuck in traffic, the vents will get up to 55-56 degrees and the cabin temp gets above 80. Then again, it is very hot and humid where I live and it's better than nothing

 

[Snowflake White]

I think it could be there is some regular outside air mixed in with the refrigerant, that slight mixture of refrigerant an air will cool but not as well as a properly evacuated system where a vacuum was pulled on the system all air removed and pure 134a installed. This will also cause odd pressure readings too.

 

[Snowflake White]

I would love to have 45 degree air all the time. If I'm stuck in traffic, the vents will get up to 55-56 degrees and the cabin temp gets above 80. Then again, it is very hot and humid where I live and it's better than nothing

Like somebody else asked...is the suction line (large diameter line) very cold and sweating all the way UP TO but NOT including the compressor itself?

 

[92saturnsl2]

I think it could be there is some regular outside air mixed in with the refrigerant, that slight mixture of refrigerant an air will cool but not as well as a properly evacuated system where a vacuum was pulled on the system all air removed and pure 134a installed. This will also cause odd pressure readings too.

I assumed the OP evacuated the system before refilling, I didn’t realize he just drained and filled.

I second this, it’s imperative the the system be put under vacuum before adding the refrigerant. This should be done with a vacuum pump and manifold gauge set, both of which are relatively inexpensive.

If you skip this step you’ve introduced air and moisture into the system which can cause all sorts of problems.

 

[eljefino]

I think it could be there is some regular outside air mixed in with the refrigerant, that slight mixture of refrigerant an air will cool but not as well as a properly evacuated system where a vacuum was pulled on the system all air removed and pure 134a installed. This will also cause odd pressure readings too.

Yeah and every time you frig with it especially during a heat wave you're letting some humidity in, the leftovers in the hose between the can and the valve.

 

[Jonas]

What are the pressures at idle? Then revved up around 200

I think it could be there is some regular outside air mixed in with the refrigerant, that slight mixture of refrigerant an air will cool but not as well as a properly evacuated system where a vacuum was pulled on the system all air removed and pure 134a installed. This will also cause odd pressure readings too.

I hope not. I pulled a vacuum for almost an hour and was careful to purge the lines and all that. My mechanic said he did the same. It took us both about an hour and a half and we got the same results.

 

[mightymousetech]

Edit: NVM

 

[Jonas]

Recap: 37-38 degrees on the interstate, 50+ at idle.

 

[Snowflake White]

Recap: 37-38 degrees on the interstate, 50+ at idle.

I wonder if the fan motor for the condenser is "failing" but not failed. It isn't uncommon over time for an electric motor like this to start slowing down over time, so it will appear things might be normal but the fan speed isn't up the to the job. Do you have a dual speed system where the fan will turn on high speed in high heat and humidity situations?? If so check to make sure the high speed fan works.

 

[demarpaint]

I assumed the OP evacuated the system before refilling, I didn’t realize he just drained and filled.

I second this, it’s imperative the the system be put under vacuum before adding the refrigerant. This should be done with a vacuum pump and manifold gauge set, both of which are relatively inexpensive.

If you skip this step you’ve introduced air and moisture into the system which can cause all sorts of problems.

I agree, and I didn't realize that either. When messing with an AC system, that had a leak and/or was open to the environment the receiver dryer should be replaced. A lot of people skip that step for a number of reasons. Either way the system has to be vacuumed down and held in vacuum for at least an hour to check for leaks and boil off moisture, then charged by weight, not pressures. Any other way almost always leads to poor cooling. Improper blend door function can cause problems as well. But after re-reading this thread it sounds to me like the job was not done properly, and there might be other issues.

 

[Jonas]

I wonder if the fan motor for the condenser is "failing" but not failed. It isn't uncommon over time for an electric motor like this to start slowing down over time, so it will appear things might be normal but the fan speed isn't up the to the job. Do you have a dual speed system where the fan will turn on high speed in high heat and humidity situations?? If so check to make sure the high speed fan works.

That's what I'm thinking. I think the fan has two speeds and I've read on GenVibe about high/low fan relays going bad, but I really have no Idea how fast should be spinning or how to tell. I also think it's an airflow/heat issue because the AC is much colder when I first start the car in the morning. I'll look in to it.

 

[Jonas]

I agree, and I didn't realize that either. When messing with an AC system, that had a leak and/or was open to the environment the receiver dryer should be replaced. A lot of people skip that step for a number of reasons. Either way the system has to be vacuumed down and held in vacuum for at least an hour to check for leaks and boil off moisture, then charged by weight, not pressures. Any other way almost always leads to poor cooling. Improper blend door function can cause problems as well. But after re-reading this thread it sounds to me like the job was not done properly, and there might be other issues.

The system was vacuumed and it held vacuum as well. The drier was also replaced. Again, it cools down considerably as I drive, but whenever I stop it creeps back up. The blend doors may be an issue, but all I can tell is when I removed the glove box door, I could see plastic gears turning when I tuned the knobs. That probably doesn't tell much. One vent has almost no airflow, but the other three are blowing hard. The vent furthest from the evaporator is a little warmer, but I thought that was normal.

 

[demarpaint]

The system was vacuumed and it held vacuum as well. The drier was also replaced. Again, it cools down considerably as I drive, but whenever I stop it creeps back up. The blend doors may be an issue, but all I can tell is when I removed the glove box door, I could see plastic gears turning when I tuned the knobs. That probably doesn't tell much. One vent has almost no airflow, but the other three are blowing hard. The vent furthest from the evaporator is a little warmer, but I thought that was normal.

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..............

 

[92saturnsl2]

The system was vacuumed and it held vacuum as well. The drier was also replaced. Again, it cools down considerably as I drive, but whenever I stop it creeps back up. The blend doors may be an issue, but all I can tell is when I removed the glove box door, I could see plastic gears turning when I tuned the knobs. That probably doesn't tell much. One vent has almost no airflow, but the other three are blowing hard. The vent furthest from the evaporator is a little warmer, but I thought that was normal.

What are the gauge readings at idle then?

 

[Jonas]

What are the gauge readings at idle then?

I don't remember. I can rent another set of gauges if need be.

 

[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..............

I sprayed the condenser with water and the vent temp dropped 5-6 degrees. The fan also got quieter (kicked down to low?) Also, the water was brown as it drained off. The vent temp dropped a tad just by opening the hood. I charged it by weight-the max charge is 16.46 oz and I got 16.09 in there.

 

[wtd]

I sprayed the condenser with water and the vent temp dropped 5-6 degrees. The fan also got quieter (kicked down to low?) Also, the water was brown as it drained off. The vent temp dropped a tad just by opening the hood. I charged it by weight-the max charge is 16.46 oz and I got 16.09 in there.

Have you checked the area between the condenser and radiator to see if there are any leaves or debris in there? I would also try spraying water on all sides of the condenser and radiator to make sure they are both clean. If they are dirty or has stuff blocking them, your fans will not be able to pull air through both of these components effectively at idle. The brown water draining off the condenser after spraying it tells me there is a lot of dirt in it. I use one of these to clean out my radiators and it works very well. https://www.amazon.com/Radiator-Gen...keywords=radiator+genie&qid=1625087857&sr=8-3

Are all of your plastic air dams on the front of the vehicle intact. A lot of times these direct the airflow toward your condenser and radiator.

Are you charging with cans and how are you measuring your charge?

 

[92saturnsl2]

I don't remember. I can rent another set of gauges if need be.

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.

 

[Jonas]

Have you checked the area between the condenser and radiator to see if there are any leaves or debris in there? I would also try spraying water on all sides of the condenser and radiator to make sure they are both clean. If they are dirty or has stuff blocking them, your fans will not be able to pull air through both of these components effectively at idle. The brown water draining off the condenser after spraying it tells me there is a lot of dirt in it. I use one of these to clean out my radiators and it works very well. https://www.amazon.com/Radiator-Gen...keywords=radiator+genie&qid=1625087857&sr=8-3

Are all of your plastic air dams on the front of the vehicle intact. A lot of times these direct the airflow toward your condenser and radiator.

Are you charging with cans and how are you measuring your charge?

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.

 

[Yah-Tah-Hey]

55 at the vent is not good, I can see why you'd be sweating. I went through that last summer with my 88 E-150. I had two leaks, one at the high side Schrader valve and the other at an O-ring in a line in front of the condenser. I addressed both issues, replaced the receiver drier, pulled vacuum and weighed the charge. It is blowing nice and cold now.

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