A/C freezing up

[family KJ]

I have had many cars that do this. I have already changed out my evaporator, compressor, condensor (florida a/c works OT) and whatever else has to do with the a/c. Who can tell me what is happening when after a while of driving, 45 mins or so, the a/c stops cooling, I have to run it on vent for about a minute or so, (to defrost I call it) then it is good for another 45 mins. What it is? Thanks

 

[kj924]

I would say either the expansion valve is not functioning properly, or the system needs to be topped off. A refrigerant system if worked too hard from lack of refrigerant will freeze up. Check for leaks first though.

 

[family KJ]

Thanks, is there a way I can test, or does a "qualified a/c tech" need to put some kind of guage of pressure test on the lines.

 

[tjkj2002]

The evap freezing is not due to under charged state,poor performance is the result from a under charged state.

Sounds like a bad low pressure switch..............

A/C LOW PRESSURE SWITCH
DESCRIPTION
The a/c low pressure switch is located on the top of
the accumulator. The switch is screwed onto an accumulator
fitting that contains a Schrader-type valve,
which allows the switch to be serviced without discharging
the refrigerant system. The accumulator fitting
is equipped with an O-ring to seal the switch
connection.
OPERATION
The a/c low pressure switch is connected in series
electrically with the a/c high pressure switch,
between ground and the Powertrain Control Module
(PCM). The switch contacts open and close causing
the PCM to turn the a/c compressor clutch on and
off. This regulates the refrigerant system pressure
and controls evaporator temperature. Controlling the
evaporator temperature prevents condensate water
on the evaporator fins from freezing and obstructing
air conditioning system air flow.
The a/c low pressure switch contacts are open
when the suction pressure is approximately 141 kPa
(20.5 psi) or lower. The switch contacts will close
when the suction pressure rises to approximately 234
to 262 kPa (34 to 38 psi) or above. Lower ambient
temperatures, below approximately -1° C (30° F), will
also cause the switch contacts to open. This is due to
the pressure/temperature relationship of the refrigerant
in the system.
The a/c low pressure switch is a factory-calibrated
unit. It cannot be adjusted or repaired and, if faulty
or damaged, it must be replaced.

 

[kj924]

Read:

http://www.inspectapedia.com/aircond/ACCoilFrost.htm

 

[tjkj2002]

Read:

http://www.inspectapedia.com/aircond/ACCoilFrost.htm

Home AC systems are different them automotive AC systems,use different refrigerant also with different characteristics.

 

[Ry' N Jen]

Speaking of Liberty A/C...

We just had ours recharged!
Yippy!

Another $300.00!*


* Or something like that!
I wasn't there, I left that up to Jen to sort out!

 

[kj924]

Home AC systems are different them automotive AC systems,use different refrigerant also with different characteristics.

Uh no....refrigeration principals are the same, no matter where you put the system.....

 

[Ry' N Jen]

And I stayed at a Holiday inn!

 

[kb0nly]

Sounds like a bad low pressure switch to me also. We had this happen on the Dodge Neon we used to have and also later on a Dodge Caravan. Both times replacing the low pressure switch and recharging the system fixed it once and for all.

 

[kj924]

And I stayed at a Holiday inn!

Hey Ryan, I stayed at a Holiday Inn once.......once. I must know everything

 

[jnaut]

Speaking of Liberty A/C...

We just had ours recharged!
Yippy!

Another $300.00!*


* Or something like that!
I wasn't there, I left that up to Jen to sort out!

Did you have the leak fixed?

 

[Banditsteve]

Holiday Inn............

I heard something years ago but I don't know if its true, and that is Stevie Wonder stays in Holiday Inn hotels whenever he goes anywhere cos all the rooms are identical apparently??????????? Cue the Stevie Wonder jokes? Maybe not!! Hehe

 

[tjkj2002]

Uh no....refrigeration principals are the same, no matter where you put the system.....

Principles are the same but the how they function is totally different.You can't use one to trouble shoot the other and vice-versa.

 

[belvedere]

Probably is the switch. That being said, the same principles absolutely do apply to both systems, as in: lower low side pressure = lower evap temp. This is Basic A/C 101 stuff.

 

[mag03kj]

If anybody knows what they are talking about it will be TJKJ2002!!!

 

[Ry' N Jen]

Did you have the leak fixed?

The dealer recharged the A/C and added a ultraviolet dye to the system
and told us to drive the vehicle for the next 14 days.
At that time they will check to see if there are any leaks and where they
are.

Cheers
Ry'

 

[Porkchop]

Principles are the same but the how they function is totally different.You can't use one to trouble shoot the other and vice-versa.

Dito X2
I have to back TJKJ he is so right on this.

 

[Porkchop]

The dealer recharged the A/C and added a ultraviolet dye to the system
and told us to drive the vehicle for the next 14 days.
At that time they will check to see if there are any leaks and where they
are.

Cheers
Ry'

This is what a good dealer schould do

 

[family KJ]

Thanks guys...next question... Can I replace this myself without de-pressurizing (if that is a word) the system... Or do I need an a/c mech.

I do have the Chilton manual...I can look it up and try to figure it out.