Its summer here and my A/C doesn't seem to blow real cold anymore and my a/c compressor cycles on and off every 6sec. I had the dealer look at it and they said its normal.(the guy acted like the didn't really want to look at it so for all i know he took it in the back and didn't even look at it)

I bought an A/C gauge set and took some readings when the truck was off and cold the truck sat all day. I hooked up the gauges and the got a static pressure of 88psi low side and 90psi high side and the temp was 80 degs out

With truck started and a/c set to max the low side gos up to 45psi then drops to 18psi then repeats every 6 secs or so is this normal i don't remember it cycling so much before but really never paid attention till it didn't blow real cold.

Also I'm about ready to pull the trigger on a couple 12'' e-fans to stick on the front of the a/c compressor but not sure how to wire it some people say to wire it to turn on with the a/c compressor but with my a/c compressor turning on and off every 6 secs that can't be good for the e-fans.


sorry for the long post

Thanks

 

My dad says I may have a clogged Orifice tube anyone has pics of where the Orifice tube is located on a 2007 F-150

 

in for answers I am having the same problem.. my cabin just wont get cold and my a/c was just recharged 3 weeks ago and had dye added to system to check for leaks. they said there were none.

possibly my mixing door is bad? anyone know how to check or how hard replacing one is?

 

Yea it sucks in the summer when your a/c is not working like it should.
I did the heater hose valve a couple weeks ago and I really didn't notice a difference.

I parked next to a F-150 same year range as mine today at the gas station and noticed 2 things 1 his a/c compressor didn't cycle like mine i couldn't even hear it and the guy was sitting there with the truck running for awhile
Second thing I notice was a lot of water dripping under his truck from the a/c. My truck used to do that but not anymore

Also my brother brought to my attention was when i used to park my truck and get out we would hear a hissing sound for a short time I researched and found this normal back then but now it doesn't do that.

 

The efans aren't going to help an A/C issue, they are purely used as a substitute for the stock mechanical fan. Your A/C system is having issues, I'd take it to a shop that knows/wants to work on them. It could be low on R134, but that's also a sign of a refrigerant leak. Your A/C won't drip (condensation) much if it's cycling on and off every 5 seconds.

 

At idle with the A/C on high is when to take the readings. To accurately diagnose, you have to look at the low pressure, high pressure, and ambient temperature.

Generally speaking, with the truck at idle, ambient temperature over 60°F, and the A/C on high (not max/recirculating), the compressor should stay on. The cycling and low-pressure readings you describe is typical of a low-charge condition. When the low and/or high pressure in the system hits a certain point, it shuts the compressor off momentarily so it can remain in the optimal area.

FYI, static pressure does not tell you anything. That number will vary wildly based on ambient and under hood temperatures.

To diagnose a clogged orifice tube, you must be able to read the high and low pressure side.

The simplest solution is generally the right one. You have a small leak somewhere and it's now low on refrigerant. And I'll just put the warning here while I'm at it. Do not overcharge the system or damage will occur.

 

sorry in 2009 these trucks started to utilize a H-block that is mounted on the firewall, this replaces the orifice tube.

 

Could you explain what a H-block is please. On O'reillys web the have a orifice tube didn't see anything for a H-Block


Thanks

 

Quit worrying about the damn orifice tube. Fix the freon charge/leak issue first, then see if anything else is wrong. The tube doesn't have anything to do with your compressor cycling on/off so quickly.

 

I concur.

 

I was just asking what an H-block was never heard of it. My bad for wanting to learn what it was.

I had a new can of 12oz 134a and added around 6oz and I'm guessing because the can feels half full. Now the a/c compressor stays on and a/c blows colder.
i only added half the can because i didn't want to overcharge the system

Took a reading with my manifold gauge set and the The low pressure side stays at 25 and the high side is 225 and this is with the truck running and max a/c

i used my friends snap-on A/C electronic Leak Detector (its the sniff type ) but i didn't find any leaks.

 

"H block" he means a thermostatic expansion valve, or TXV for short


efans can help move more air at idle, but can actually restrict air if left on at highway speeds

 

High side pressure should roughly be double your ambient temp

 

For r134a pressures go to - http://www.aerocousa.com/UploadFile/...3143822361.jpg

The "TXV" is a metering device like the orifice tube. a google search will explain it.

i just installed a pair of 3000cfm each fans and found my compressor seal is leaking and about to take out my clutch, so new pump in the near future.

Hope this helps you out.

 

Thanks for the info did you mount your fans on the a/c condenser or did you do a full E-fan swap. What size fans are you running.