[ImperialCrown]

Welcome to Allpar. You should be very leery on adjusting the refrigerant amount in the system unless you have a good reason to. If the system is low, you have a leak that has to be addressed first.
You may be able to view the gauge set while going down the road for when it is acting up. That is the time when you want to diagnose this.
The instrument cluster (CCN) is the module that controls the A/C system. It can store fault codes and offer sensor information that may help in diagnostics. You may need an advanced scan tool to access this information. If the evaporator is icing up, you will lose cooling while driving.
The TIPM and PCM control the compressor which is engaged all the time. The displacement is varied according to A/C demand. These modules also can store fault codes and system information.
Find factory service information in chapter 24 here: 2007 DODGE Caliber Service Manual

 

[Bob Lincoln]

When you say you 'purged' the system, does that mean you vented all the freon out and refilled again?

When servicing A/C, you MUST draw a vacuum on an empty system before filling. Otherwise, you have air and moisture trapped in there, which will reduce both the life and performance of the system.

It's important to diagnose the problem before trying to service it, and that includes both high and low side gauge readings, as well as vent temperature and ambient temperature. It's important to study and understand how to service A/C before working on it, or you can get hurt and do damage. Ask me how I know. I have taught myself and have done several conversions and services successfully, with the proper equipment.

 

[Larbabe]

Thanks, Imperial. I'll try the gauges while driving and see if my reader can get the codes.

Bob, I read that if you vent the system but close it before it completely empties you don't have to use a vacuum pump on it. Maybe the one who wrote that was up in the night?

When I filled it the first time, I went to the top of the FULL mark on the low side. Later I learned that the actual pressure should be quite a bit higher. The scale on my gauge is misleading. I filled it to the new setting but didn't see any change in the problem. I did check ambient temp outside and actual temp from the center of the console. At idle it's putting out 60 deg. Then the faster I drive the closer it gets to the ambient temp. At freeway speed they are the same.

I haven't been able to check the high pressure, though. The fitting is at the end of my reach in that tight space. I could get it on the end, but not push hard enough to lock in place. Using a lever I got it on, but it leaked. Gasket is missing in the quick connect! Found one but it's too tight to go on now. Will have to try to shave off the outer edge a bit.

Someone suggested the blend door may not be working properly. But according to the manual the whole unit has to come out of the car to work on that.

It would be helpful to know whether the problem is under the hood or dash. Is there a place I could put a thermometer sensor that would tell me if the system actually keeps cooling while driving? If it doesn't, then it could be compressor, pressure switch or something like that. If it does, then it could be air routing inside.

 

[Bob Lincoln]

No, you cannot refill without drawing a vacuum. It's not true that no air or moisture can get in unless you fully vent the system. You almost certainly have a leak if the pressure was low (and I don't see that you posted any pressure readings in psi). A leak means that air and moisture can and will get in. Consider that if you are venting out one of the ports (which is illegal and harmful to the environment), a leak in another place can be suctioning air in at that point. You must draw a vacuum because air and water vapor will not only take up space needed for refrigerant, but will react with the oil and form corrosive compounds that will reduce the life of the system.

When refilling, you must monitor not only low and high pressures, but also add the proper weight of refrigerant. Do not rely on pressure gauges alone. The weight of the system charge is on a sticker underhood.

But before any refill, you must find and fix the leak. You can buy a can of R134a with UV dye in it, and put a can in an empty system just to circulate the dye, then look with a UV penlight to see where the leak is. Auto parts stores sell a penlight and protective goggles for about $22.

 

[Larbabe]

Here's an update:

Was able to get the high pressure gauge line connected, and bungee corded the set on top of the hood so I could see what it's doing as I drive. At idle, the low is 50 and the high is 200. At 55 the low is around 70 and the high is below 100. Guess that means the problem is under the hood, not in the HVAC housing in the car.

Thanks for the heads-up, Bob. BTW, I only "allegedly vented the system." (In case anyone's listening)

 

[ImperialCrown]

If your scan tool can read evaporator temperature and compressor 'duty', that might help diagnose this. It should not allow the evap to freeze.
If the sensors and modules see the evap as being too cold, they will cut back the compressor duty to compensate. This will bring the high and low sides closer together as it believes that less work has to be done. It could be wrong because of wrong information.
The blend door could be stuck halfway blowing lukewarm air and not swinging to the full-cold position, although it does start out blowing cool.
As stated, the compressor is engaged all the time on these. There is no cycling compressor clutch. The modules vary the compressor output by sensing and adjusting the swash-plate throw, which is like a variable stroke piston pump. Why it may be doing this or what is happening here will help diagnose your issue. This may be beyond the scope of a standard 'code reader'.

 

[cochise7969]

What happened with this?! My Caliber is doing the exact same thing!!! Cold air out when stopped, warm air when driving. (Help me get the wife off my butt)

 

[Bob Lincoln]

Probably low on freon, maybe a leak.

 

[cochise7969]

I tried that Hooked up AC PRO and it was in the red. I hope Larbabe fills me in.

 

[cochise7969]

Looks like the FAN for the AC condenser will not ever turn on, I guess if you have no air going through the condenser, something about making liquid into gas won't happen making the AC cooling turn on intermittently. Is there a fan relay I should check? I figured if it was a fan relay the check engine light would turn on. Should I just replace the fan? F the relay?

 

[Bob Lincoln]

Is the compressor turning on? It should not, if the fan doesn't also turn on.

 

[ImperialCrown]

The Caliber compressor is always 'on'. It is a VDOT, there is no compressor clutch or relay. The radiator/condenser fan should come on according to high-side pressure. No fan relay either. It is run by a duty-cycle driver in the TIPM according to demand.
http://www.polarbearinc.com/Articles/Variable%20Displacement%20Compressor.pdf

 

[mrmotormd]

i know this is an old thread but i would seriously like to know where the moderators are getting there info from. this entire thread pointed to the fact that this man had a cooling fan problem and you guys seems more focused on him purging his ac without pulling a vacuum. fyi the dodge caliber DEFINATELY

 

[mrmotormd]

i know this is an old thread but i would seriously like to know where the moderators are getting there info from. this entire thread pointed to the fact that this man had a cooling fan problem and you guys seems more focused on him purging his ac without pulling a vacuum. fyi the dodge caliber DEFINATELY HAS cooling fan relays. the 07 has an entire cooling fan relay box on the right of the cooling fans and others are run via a solid state relay bolted to the core support/front bumper. high side pressure rises as the engine rpms increase and the demand for more air circulation (high speed condensor fan) is needed. if heat is not removed from the condensor via high speed cooling fans no will be made on the gas side of the expansion valve. cooling fans are a huge problem with this vehiclee and the problem almost always stems from a relay power problem. the tipm DOES kill power to many components on this vehicle and should be checked to ensure that proper power is being sent to cooling fan relay module.

 

[Bob Lincoln]

I guess if you had read closely, you'd see that two different people posted their problems here. The first one clearly stated that he had not pulled a vacuum before recharging the system, which is a faulty procedure that leads to poor cooling and reduced system life.
The second poster appeared to have a fan or fan control problem. Two different issues, so two different responses.
And responses are in no way limited to moderators. Lots of members contribute their knowledge.