AC experts?
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Laughing Gas
Joined: May 2017
Posts: 969
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AC experts?
Long story short I've been fighting with 60 degree vent temps at idle. System has been charged properly, I cleaned the condenser, and just the other night cleaned out the evaporator. It was covered in crap. After reinstalling everything I turned it on to test the system. At idle, in 82 degree ambient, the vent temp got all the way down to 46 degrees. So I got out of the truck, leaving it on, to put some tools away. A couple of minutes later I got back in to check temps and it was 55 and climbing. Last night, same 82 ambient, I could not get it lower than 60 at idle again.
Anyone know what might have happened? Why was it able to get down to 46 (and dropping still) but then go back over 50 to never see the 40s again? All running conditions were the same. Which doesn't matter because the night it saw the 40s I hadn't done anything to affect the system other than allow it to continue to idle? I'm stumped.
Anyone know what might have happened? Why was it able to get down to 46 (and dropping still) but then go back over 50 to never see the 40s again? All running conditions were the same. Which doesn't matter because the night it saw the 40s I hadn't done anything to affect the system other than allow it to continue to idle? I'm stumped.
Fleet Owner
Joined: Apr 2008
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From: 0,0,1
What vehicle?
For your issue my first thought is the condenser fan isn't coming on or if it is it is not spinning fast enough to draw sufficient air through the condenser. If it cools good while driving over 35 MPH then the fan is the likely culprit.
For your issue my first thought is the condenser fan isn't coming on or if it is it is not spinning fast enough to draw sufficient air through the condenser. If it cools good while driving over 35 MPH then the fan is the likely culprit.
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Laughing Gas
Joined: May 2017
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Well the interesting part is the first night when I saw the 46 at idle, the truck wasn’t warmed up yet so the fan wasn’t on. But last night, same ambient temps, the truck was warmed up and the fan was turning faster. But it wouldn’t get colder than 60 degrees at the vent.
Tuned
Joined: Jan 2002
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From: Wasilla
First thing, make sure everything, radiator, condenser, and inner cooler are clean, then get out on the highway. If the AC works normally at highway speed, then you have a cooling fan issue. If the highway test indicated a cooling fan issue, then you probably need a new fan clutch. The exception is if your EGR valve has been deleted. A missing EGR valve screws up correct cooling fan function. So if the EGR valve has been removed, get one and plug it back in. Good luck, Russ
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Laughing Gas
Joined: May 2017
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Likes: 30
First thing, make sure everything, radiator, condenser, and inner cooler are clean, then get out on the highway. If the AC works normally at highway speed, then you have a cooling fan issue. If the highway test indicated a cooling fan issue, then you probably need a new fan clutch. The exception is if your EGR valve has been deleted. A missing EGR valve screws up correct cooling fan function. So if the EGR valve has been removed, get one and plug it back in. Good luck, Russ
at idle, the cooling fan spins at around 850 rpm. I guess that’s just not enough.
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Laughing Gas
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I have verified it functions properly.
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Hotshot
Joined: Jan 2004
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From: St Louis
If you want maximum air conditioning cooling, the valve must be CLOSED in MAX A/C position.
Prep the truck for testing by following the prescribed steps in the service manual, connect your gauge set, and perform proper diagnostics instead of guessing.
Vent outlet temps are good for telling you when the system is working well or not but they cannot provide insight into what the system is doing (or not) and why.
Record and report the readings along with the ambient testing conditions for analysis assistance, if needed.
Prep the truck for testing by following the prescribed steps in the service manual, connect your gauge set, and perform proper diagnostics instead of guessing.
Vent outlet temps are good for telling you when the system is working well or not but they cannot provide insight into what the system is doing (or not) and why.
Record and report the readings along with the ambient testing conditions for analysis assistance, if needed.
Thread Starter
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Laughing Gas
Joined: May 2017
Posts: 969
Likes: 30
If you want maximum air conditioning cooling, the valve must be CLOSED in MAX A/C position.
Prep the truck for testing by following the prescribed steps in the service manual, connect your gauge set, and perform proper diagnostics instead of guessing.
Vent outlet temps are good for telling you when the system is working well or not but they cannot provide insight into what the system is doing (or not) and why.
Record and report the readings along with the ambient testing conditions for analysis assistance, if needed.
Prep the truck for testing by following the prescribed steps in the service manual, connect your gauge set, and perform proper diagnostics instead of guessing.
Vent outlet temps are good for telling you when the system is working well or not but they cannot provide insight into what the system is doing (or not) and why.
Record and report the readings along with the ambient testing conditions for analysis assistance, if needed.
I wish I had a service manual. Need to look for one (even if I have to pay) again.
last readings at 92 ambient were 37/260 if I remember correctly
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Laughing Gas
Joined: May 2017
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also, I find that with a couple of ounces more it puts out “warmer” air at the vent. Only a couple of degrees but still warmer. So I decided to leave the refrigerant charge where it’s at.
Fleet Mechanic
Joined: Jan 2016
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Lead Driver
Joined: May 2003
Posts: 9,303
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From: Lyndonville, Vermont
Best to have it evacuated and all the moisture boiled off and recharged to make sure the amount is good....Back in the day I would charge till the return line at the compressor was getting cold... Its easy to over charge. Temps will go down if you do.
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Laughing Gas
Joined: May 2017
Posts: 969
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I get these problems in the shop quite a bit. Since you don't know the volume of refrigerant in the system it needs to be recycled and the system recharged with the correct amount. If you aren't sure of the charge then start over and measure the correct amount of Freon into the system. No one here can help you if you don't know.