AC Questions

mxer201 · 06-24-2009, 02:07 PM

The ac in my 98 Dakota doesn't cool the cab as quick as I think it should. The compressor is engaged, not cycling, and a lot of moisture is dripping from the evaporator. I haven't had the system checked yet but I'm wondering if the evaporator is clogged. And is a constant cycling compressor a sign of low R134?

silverhairdeere · 06-24-2009, 02:41 PM

i would try a shot of r134 first , i always thought cycleing of the compressor was normal ? i could be wrong though .

shd

bradrhale · 06-24-2009, 02:55 PM

remember that thermodynamics is not perfect. heat transfer is always part of the equation and being as hot as it is lately, it will take some time to cool a cabin off. alot of water coming through the condensate drain is normal especially if it is working hard.
is the compressor cycling or not?? you mentioned not cycling which is possible if you are getting enough air through the condenser coil. this will keep the head pressure down so that it will not cycle. you also mentioned that it cycles alot. if your head pressure gets high, than the compressor will shut off. this is normal operation if you are idling. going down the highway will keep the compressor running and this is partly why it cools so much better at highway speeds rather than stop and go traffic.
i wouldnt be concerned about putting freon in the system until you have done a pressure test to verify that the system is low, which i doubt that the way you describing your issue.

mxer201 · 06-24-2009, 03:29 PM

Quote:

Originally Posted by bradrhale

remember that thermodynamics is not perfect. heat transfer is always part of the equation and being as hot as it is lately, it will take some time to cool a cabin off. alot of water coming through the condensate drain is normal especially if it is working hard.
is the compressor cycling or not?? you mentioned not cycling which is possible if you are getting enough air through the condenser coil. this will keep the head pressure down so that it will not cycle. you also mentioned that it cycles alot. if your head pressure gets high, than the compressor will shut off. this is normal operation if you are idling. going down the highway will keep the compressor running and this is partly why it cools so much better at highway speeds rather than stop and go traffic.
i wouldnt be concerned about putting freon in the system until you have done a pressure test to verify that the system is low, which i doubt that the way you describing your issue.

The last part about a compressor cycling a lot was just a general question asking if that is an indicator of low R134. I should have been more clear. The compressor in my truck was not cycling when I checked it but I will examine it again.

bradrhale · 06-24-2009, 06:56 PM

if the clutch stays engaged and cools, than i would run it. a frozen evap coil is not going to give off condensate as it freezes and will not let it run out. personally, i think you are fine. these hot temps are difficult to contend with.

mxer201 · 06-25-2009, 05:44 PM

An update. Start the truck, turn AC on, the compressor is engaged. Once on the highway I held my hand over the vent. The air is nice and cool then it starts to warm. Then it gets cool for a few seconds then warm again. So the compressor must be cycling? Takes about 20 minute to drive home. Once home, pop the hood, leave motor running with AC on, the compressor still engaged, not cycling even after a few minutes. At idle the RPM is around 600 and on the highway never over 1800. Lots of moisture dripping from evaporator.

hotrodpc · 06-25-2009, 08:19 PM

Yep, in 102-105 humid heat, my vehicle is taking a long time to get it there, but once it does, its blowing 48 degrees. Thats exceptional for 102 degrees and humid out. If you have your AC on recirculate, which most do, that is usually MAX AC setting, then roll down your windows for the first couple of minutes and get some cooler air into the cabin, so you are reciruclating and cooling 100 degree air instead of 160 degree air from the windows being up. Or if you like the 160 degree heat, put the AC on normal or NON recirculate then it will cool outside fresh air, then once the cabin is starting to cool, take it up to max AC or recirculating.

leolkfrm · 06-26-2009, 03:20 PM

check the temp flapper!

06-24-2009, 02:07 PM	#1
mxer201 Full Member Join Date: Feb 2007 Posts: 42	AC Questions The ac in my 98 Dakota doesn't cool the cab as quick as I think it should. The compressor is engaged, not cycling, and a lot of moisture is dripping from the evaporator. I haven't had the system checked yet but I'm wondering if the evaporator is clogged. And is a constant cycling compressor a sign of low R134?

06-25-2009, 08:19 PM	#7
hotrodpc Senior Member Join Date: Jul 2008 Location: OKC, OK Posts: 2,847	Yep, in 102-105 humid heat, my vehicle is taking a long time to get it there, but once it does, its blowing 48 degrees. Thats exceptional for 102 degrees and humid out. If you have your AC on recirculate, which most do, that is usually MAX AC setting, then roll down your windows for the first couple of minutes and get some cooler air into the cabin, so you are reciruclating and cooling 100 degree air instead of 160 degree air from the windows being up. Or if you like the 160 degree heat, put the AC on normal or NON recirculate then it will cool outside fresh air, then once the cabin is starting to cool, take it up to max AC or recirculating. __________________ *Winners Never Quit, Quitters Never Win !!!*

06-26-2009, 03:20 PM	#8
leolkfrm Senior Member Join Date: Mar 2008 Location: N.Y. Posts: 4,220	check the temp flapper! __________________ 4 wheels move the body 2 wheels move the soul B.W.A.I

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
got a few questions	nativebroncofan	Chevy Truck Forum	18	04-11-2009 01:53 PM
A few questions . . .	skirch56	Ford Truck Forum	4	04-07-2007 11:28 AM
New guy says hi and I got some questions	Burb fan	General Truck Forum	7	11-28-2006 08:51 AM
2 questions	WickedIronhead	Chevy Truck Forum	6	07-05-2006 01:52 PM
More Questions ?	russty08	Chevy Truck Forum	5	05-23-2006 09:21 PM

06-24-2009, 02:41 PM	#2
silverhairdeere Senior Member Join Date: Feb 2008 Location: land between the lakes tn Posts: 1,118	i would try a shot of r134 first , i always thought cycleing of the compressor was normal ? i could be wrong though . shd

06-24-2009, 02:55 PM	#3
bradrhale Senior Moderator Join Date: Apr 2006 Location: Texas Posts: 7,831	remember that thermodynamics is not perfect. heat transfer is always part of the equation and being as hot as it is lately, it will take some time to cool a cabin off. alot of water coming through the condensate drain is normal especially if it is working hard. is the compressor cycling or not?? you mentioned not cycling which is possible if you are getting enough air through the condenser coil. this will keep the head pressure down so that it will not cycle. you also mentioned that it cycles alot. if your head pressure gets high, than the compressor will shut off. this is normal operation if you are idling. going down the highway will keep the compressor running and this is partly why it cools so much better at highway speeds rather than stop and go traffic. i wouldnt be concerned about putting freon in the system until you have done a pressure test to verify that the system is low, which i doubt that the way you describing your issue.

06-24-2009, 06:56 PM	#5
bradrhale Senior Moderator Join Date: Apr 2006 Location: Texas Posts: 7,831	if the clutch stays engaged and cools, than i would run it. a frozen evap coil is not going to give off condensate as it freezes and will not let it run out. personally, i think you are fine. these hot temps are difficult to contend with.

06-25-2009, 05:44 PM	#6
mxer201 Full Member Join Date: Feb 2007 Posts: 42	An update. Start the truck, turn AC on, the compressor is engaged. Once on the highway I held my hand over the vent. The air is nice and cool then it starts to warm. Then it gets cool for a few seconds then warm again. So the compressor must be cycling? Takes about 20 minute to drive home. Once home, pop the hood, leave motor running with AC on, the compressor still engaged, not cycling even after a few minutes. At idle the RPM is around 600 and on the highway never over 1800. Lots of moisture dripping from evaporator.