In need of some AC info

TJ in KY · May 23, 2016

I am in Florida for a short vacation and the air conditioner on my 2012 Buick Enclave stopped working. I had the charge checked and it was low by about a pound.
I was wanting to know what the temperature drop should be. I put a stem type thermometer in the AC vent and with the outside air at 85 the temp in the duct was about 52. It seems to cool fine at highway speeds but sitting in traffic or at low speeds the temp in the duct is about 65 degrees. Is this normal or could it have a leak or still be low on refrigerant.
It just seems different than what I remember last summer.

mite-help · May 23, 2016

65 out the duct is high, hard to say, first thing I would check is engine cooling fan.

da.bees · May 23, 2016

I also suspect fans not running,not running fast enough or one fan not running. I don't know about the Enclave but my F-250 diesel fan modulates speed according to need. It's hard to know without fan specs and proper tools but I suppose you could put thermometer in vent,find a long hill to coast down with engine at idle. If temp rises the difference in compressor rpm is the reason for change in temp. If temp hold's steady the problem is with fan(s). While you're at it make sure nothing is covering the condenser,(did you hit a buzzard on the way down).

Cliff Nelson · May 23, 2016

Cooling good at highway speed indicates that the system is charged properly and working properly. Weak cooling at low speeds indicates cooling fan(s) not working. At highway speed the fans do not need to do anything as air is naturally forced through the radiator and condensor. What does the engine temp do when it is not cooling well?

Super-H-Mike · May 23, 2016

I find that if the vent temp isn't around 40 degrees on a hot day that the occupants will feel like the AC isn't
working very well.

4play · May 23, 2016

(quoted from post at 22:26:33 05/23/16) I find that if the vent temp isn't around 40 degrees on a hot day that the occupants will feel like the AC isn't
working very well.

I concur with this statement. I always like to at least see 45* regardless of outside temps and shoot for 40*. I know if its 50* or above you will start getting complaints. If its under or over charged you can have a higher than normal vent temp. Since it was low then you have a leak.

TJ in KY · May 24, 2016

Thanks for all the replies. I will check to make sure the fans are kicking on and watch the engine temp. Not many long hills down here da.bees, if I don't get it resolved I
will try that on the way home.

JMOR · May 24, 2016

(quoted from post at 07:42:03 05/24/16) Thanks for all the replies. I will check to make sure the fans are kicking on and watch the engine temp. Not many long hills down here da.bees, if I don't get it resolved I
will try that on the way home.

he difference between return air & output air (evaporator inlet minus evaporator outlet) is the important number, because looking only at outlet will vary so much, depending on what the inlet temperature is, that it is really a near meaningless number.

guido · May 24, 2016

Hello TC in KY,

Do you know the system pressures? Ambient temperature will determine those pressures. Sounds like you need
more refrigerant, if all is well with the rest of the system. Check the temperature at different fan
speeds. If it is coldest in the lowest speed, it needs more refrigerant,

Guido.

In need of some AC info

TJ in KY

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mite-help

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da.bees

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Cliff Nelson

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Super-H-Mike

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4play

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TJ in KY

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JMOR

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guido

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