dkdontforget

Hey everyone, i did some reasearch to why my ac was warm at idle or at a stop light but gets cold when moving, most said to check the pressures, i rented a guage set from autozone

the pressures are

L: 40~43
H: 240~245

Ambient temp is around 78

And if im correct that should be about correct for the pressures, maybe a little low...

well the thing is my A/C is at an okay coldness, it wont make you shiver but its ehh..

Right as i drive to rent the guage the A/C decides to blow ICE COLD, colder than its ever blown.

Okay now to the point

I noticed that the compressor doesnt cycle, it just stays on, and it stays on for a good 30 min, i have not seen or heard it disenage. and i know the sound because it use to a few weeks ago, it would cycle every 30-45 sec or more at a stop light.

is there any reason that it is constantly on?

ALSO only one fan turns on with the A/C the other doesnt turn on untill the car gets hot enough, is this normal?

ezone

L: 40~43
H: 240~245

Ambient temp is around 78

High side appears to be a little excessive for that ambient temp, but I don't know all your conditions....
What engine RPM were these pressure numbers taken at?
What has anyone ever done to the AC system? Recharged from cans?
Was the condensor fan running?




is there any reason that it is constantly on?

Something broke?
Usually the relay stuck on. Tap on the clutch relay and see if that makes the compressor stop running.
Or maybe the AC thermostat quit and left the comp running....
Clue: See if the condensor fan is running now


ALSO only one fan turns on with the A/C the other doesnt turn on untill the car gets hot enough, is this normal?

6th gen:
Radiator and condensor are mounted separately, correct?
Each has its own fan, correct?
Each fan is controlled independently of the other.


HTH

dkdontforget

Thanks for the reply
The ambient temp is 78 with around 50% humidity
The pressures were taken at idle
The A/C has never been serviced.
The condenser fan was running the whole time

I will try the clutch relay and get back on that

and the radiator fan is turning on and off when it gets to temp

dkdontforget

ok tapping the clutch relay did nothing, but here is something interesting i found out.

when the fan setting is at its lowest it will cycle on and off at 16 second intervals. but when i turn the fan to the high settings its just constantly on

ezone

Ok then, don't touch the freon. Appears to still have plenty, and the system has the ability to get cold enough ("ICE COLD"), it would never be able to do that if it was low on freon.
(NOTE: If it is allowed to continue operating at "far too cold", the evaporator core can turn into a huge ice cube. Stick an accurate thermometer in the center dash vent and see what temps it is running at.)


If the compressor is running and the condensor fan is on the entire time, then I'd look to the control side of the system, like the AC thermostat.

If you can get the system to run far too long (and far too cold) as before, just unplug the AC thermostat 3 wire connector and see it that allows the compressor to shut off.
(NOTE: I know what temps they generally cycle at, so my rush to disconnect the stat may not be everyone elses first step. I just want to make sure that is the entire reason it stopped cycling, and it has to be acting up to determine that.)


There is a test for the AC thermostat in the service manual, it involves checking the temps that it turns on and off at. Probably a semi-worthless test at the moment though. It would have to be in a failed mode to test bad.


HTH

ezone

This sounds like normal operation at the moment.

ezone

Before you go nuts, I'd want to know what the temps are at the dash vents.

To a certain extent, this is a normal phenomenon and is to be expected. The system becomes much more efficient with higher compressor speed (engine RPM) and more airflow (road speed).

I'd hate to send you off on a wild goose chase.....

dkdontforget

It only got that cold after a long while of running. And not literally ice cold but as cold as a brand new car would get. I will try to get a thermometer to see the actual temps
And where is the connector located?

ezone

Take readings at the dash vents.
I use an accurate digital thermometer with a rapid response time.

Temp should not get under 34 degrees, that would mean the core is colder than 32 and can freeze the water.

Cycling could be anywhere form 35ish to 48ish deg. they vary from car to car, and vary with interior temps. 4-7 degrees change between off and on cycles.

Ideally you run it on full blast/2000rpm for 10 minutes to stabilize the car and the system. See what temps are.

Low fan speed will almost always give lower vent temps because of less thermal load. Easier for the system to cycle.
High fan speed makes more thermal load and system may take far longer to cycle or not cycle at all, especially at idle.


I was trying to suggest you make certain there is a real problem before trying to "fix" anything.

dkdontforget

Alright i just bought an A/C themometer from autozone ($6.99 )
and with city driving for about 10 min it got down to 50 degrees, and the sun is pretty much set and its around 75 outside,
ill test for longer tomorrow at idle and at 2000rpm

ezone

Alright i just bought an A/C themometer from autozone ($6.99 )

Cool! I need about 3 more!
Wait up, is it digital, or a dial type?
I need digital. (I can "watch" the system cycle, by the temp ranges on the digital thermometer.)



and with city driving for about 10 min it got down to 50 degrees, and the sun is pretty much set and its around 75 outside,

50 is pretty close to a 48 cycle temp.....But is that the temp it cycles at, or is that as low as it is getting?

Fan speed?

Do you have Recirculate on, or is it set for fresh air?

You should have it on Recirc.

At 75 ambient and recirc, I would expect it should reach a cold enough temp to make the compressor cycle repeatedly even if the fan is on full blast. Not a lot of thermal load on the system.

Have you checked for how many dead bugs are trapped in the fins of the condensor? Tried to rinse them out yet?

dkdontforget

It is the dial type, didnt see any digital and if there was i probably couldnt afford it right now, i kept it on fresh air, and thats as low as it got, it wasnt cycling

fan speed was max with just the head vents going

would it be better to test it now since its cooled down and in the garage?

also there is no dead bugs or any debris

but it does have alot of bends and stuff near the bottom like this http://www.ford-trucks.com/user_gall...d=214171&.jpg=

but only at the bottom, its fine above the bumper

ezone

i kept it on fresh air, and thats as low as it got, it wasnt cycling

Use recirculate.
The system doesn't have to work as hard to cool down air that is already partly cooled and dehumidified.

Heck, that might solve all your problems.

HTH

dkdontforget

I always have it on recirc. I heard that its best to check the temps with fresh to see how well the ac is working.

But just checked in the garage max fan recirc. Got it down to 41-42 ish but there was no cycling at idle or 2k rpm.

But the heater works great! Got it up to a toasty 145 . Also something interesting. Ac cooled it from 145 to 60 in about 55 sec.

You said something earlier about testing what temps that it should cycle at?

dkdontforget

Ok i just tried again this morning it got down to 40 max fan recirc and it seems it cycles at that temp because it was cycling. is it possible that its just not efficient enough to get it that low while driving?

ezone

I heard that its best to check the temps with fresh to see how well the ac is working.

Well, yes and no, sorta... Part of the performance test is done with all the doors wide open, 1500RPM(ish), fan on full blast, BUT using recirculate...to avoid the engine heat that would be coming into the fresh air ductwork out front.


The test is something like this: Measure vent temps (L, R, Center), ambient temp, humidity, intake temp to the blower, and look it all up on a chart/graph....(Nowadays, I can plug those into a calculator.) A drop of only 25 degrees can be acceptable....Now note all the pressures and see if they are acceptable for the temps given.... There are charts to use for reference too.
Sometimes the system accepts stuff that just doesn't "feel right" to me though, but the system says it is acceptable.


The performance test doesn't have checks done at idle, because the systems just aren't efficient at low RPM.






Or, just toss the thermometer in the center vent, drive on the highway at 55-65mph for 10-15 minutes with fan on full blast, recirc, max cold, etc.....enjoy the break from the heat in the shop for a few. If it gets to cycling at all on a day like today (100) it must be decent. Hell, I'm happy if there is a 40 degree drop from the outside temps when I'm sweating my azz off.
If my glasses fog over when I get out, then it was cold!



what temps that it should cycle at?


Remember, I use digital thermometers that are pretty sensitive for this. They respond to change rapidly and measure tenths of a degree.


Most systems cycle on-off-on-off within about a 5 degree range (measured at the vent), give or take a couple degrees.
Some cars have different modes that can alter that.

But

It varies.

The core temp should always remain higher than freezing by at least a couple of degrees. If it goes below freezing, then it could become a huge ice cube, and that don't cool the car worth a crap.

That doesn't mean your vent temps will be anywhere near that cold.

On a real mild day, I could see cycle temps such as 36-40, but like I said before, it varies from car to car. An identical car might run 6-8 degrees higher and be fine.
On a nice hot day, they could be 50 from the same car, and it may take forever before it gets cool enough to cycle.
The temps usually drop slowly as everything inside the car cools down, but it can take a loooong time. You have 3-6 feet or more of ductwork and dashboard that contribute their heat before the air comes out of the dash vents, and the interior of a car can be 190*+ easily after sitting in direct sun.
Yes, I have actually checked that.





Probably more like it is cooler in the AM there.
Easier to get the AC cold.


Did you make sure the heater core water valve is completely shut off?

-------------------------------------------------------------

rant
Man, I gotta stop responding to AC questions. I can't explain it good, can't see/feel/fix it over the internet, and they really should be done by someone with professional equipment when it comes to recover/evacuate/recharging freon. ChinaZone/WallyWorld value shoppers screw it up too, and it is anyones guess what was put in it or how much.
Why do I have to be certified for AC work and be subject to scrutiny by the EPA, but any Joe Blow can walk in to those stores and buy refrigerants (that may or may not even be acceptable for mobile AC use), discharge their own system into the atmosphere, and recharge leaking systems?
/rant
//hugs a tree

dkdontforget

Thanks for the detailed reply, basically I'm just worried the compressor would burn out or go bad, I want it to last the summer. In short, should I worry about it running constantly as long as it doesn't freeze over?

ezone

If the system still has sufficient oil, it should be fine.

HTH