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Old 06-18-2017, 10:48 PM   #1
Mailbox7
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My AC isn't cold

Hello! So my AC in my car simply isn't cold. The compressor is on, the climate control is on 3 blue dots and my mechanic states that the pressures are fine (40-45psi low, and 240 High). So I'm not sure what is going on and it is beginning to get really hot out so I want to get this fixed asap and hopefully it's not expensive. Maybe a blend door is sticking? Again, compressor kicks on with no problem. Let me know! Thanks !


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Old 06-19-2017, 07:02 AM   #2
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The first step is to determine the temperature of the air coming from the dash vents. A simple digital temp gauge will work.

Let's assume that the temp is indeed higher than it should be. The next step is to determine if the heater control valve is allowing hot coolant into the heater core in the dash. The valve is located on the intake side of the engine compartment on the inner fender. There are 3 hoses on the valve. The one going into the passenger compartment must be cold. If it's not the heater control valve is suspect.

A bit of info: The heater core and the AC evaporator are stacked on top of each other. The air flow is through the heater core and then through the AC evaporator. Why? The automatic climate control (IHKA) in the dash gets temperature data from a sensor on the AC evaporator. When that temperature is too low the IHKA allows coolant to flow through the heater core to prevent the AC evaporator from freezing. The IHKA does this by pulsing voltage to the heater control valve. This valve is open unless it's getting 12VDC.
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Old 06-19-2017, 09:17 AM   #3
Alvinized52
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I had a similar intermittent symptom. Also my signal lights would stop working and other weird electrical things would stop working intermittently. My BMW mechanic could not figure it out. Then Finally my instrument cluster completely went out.... so i bought a used one for parts to get the cluster fixed. All of a sudden everything was working perfectly... including the AC. Yeah... I know.

So It could be your instrument cluster...
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Old 06-19-2017, 10:11 AM   #4
Starvega
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If the compressor is working and the pressures are correct, which you're saying they are, then it has to be the blend door.
The other thing you might check is that it's actually refrigerant in the lines and not hot air. My car does this every few years, it'll blow warm air and the lines are pressurized with air. Probably a leak somewhere but it takes like 4 years for it to leak out so I'm not fixing it lol
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Old 06-19-2017, 10:15 AM   #5
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Have it looked at by a pro tech.
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Old 06-19-2017, 10:36 AM   #6
Mailbox7
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Okay so today I turned my AC on full blast and the driver side was not cold but cooler while I was driving, and the passenger side was warm? Does this help steer anyone towards other things? Let me know thank you for all the answers


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Old 06-19-2017, 10:46 AM   #7
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You might have debris in front of the condenser. Clean it out. You have an air flow problem likely. Also make sure your fans are working.
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Old 06-19-2017, 11:37 AM   #8
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Quote:
Originally Posted by markusmarkus View Post
The first step is to determine the temperature of the air coming from the dash vents. A simple digital temp gauge will work.

Let's assume that the temp is indeed higher than it should be. The next step is to determine if the heater control valve is allowing hot coolant into the heater core in the dash. The valve is located on the intake side of the engine compartment on the inner fender. There are 3 hoses on the valve. The one going into the passenger compartment must be cold. If it's not the heater control valve is suspect.

A bit of info: The heater core and the AC evaporator are stacked on top of each other. The air flow is through the heater core and then through the AC evaporator. Why? The automatic climate control (IHKA) in the dash gets temperature data from a sensor on the AC evaporator. When that temperature is too low the IHKA allows coolant to flow through the heater core to prevent the AC evaporator from freezing. The IHKA does this by pulsing voltage to the heater control valve. This valve is open unless it's getting 12VDC.

Are you talking about a ship or an E46?!? Sounds more like an M class star freighter.

That is one awesome description of how that system works.

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Old 06-19-2017, 05:34 PM   #9
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Quote:
Originally Posted by Mailbox7 View Post
Hello! So my AC in my car simply isn't cold. The compressor is on, the climate control is on 3 blue dots and my mechanic states that the pressures are fine (40-45psi low, and 240 High). So I'm not sure what is going on and it is beginning to get really hot out so I want to get this fixed asap and hopefully it's not expensive. Maybe a blend door is sticking? Again, compressor kicks on with no problem. Let me know! Thanks !


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I just checked my pressures and they're ~ 20 psi on the low end.

It's 108 today.
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