I have an intermittent A/C blower issue that I hope someone can assist (I saw the other A/C thread, but I don't know that I have the same issue).

I have experienced while driving with the A/C on and in the recirc mode that the air will suddenly stop coming from ALL vents, but the blower can still be heard running. I will open the windows, turn the A/C to the vent mode, and flaps seem to open back up (for awhile). Over a 3 hr. trip, this may happen 4-5 times.

I checked the vacuum line per the other thread and I could not find anything obviously wrong. I am getting ready for a week long trip to warmer (95+ deg.) climates and don't want to have any cold air issues!

Can anyone help?

 

Is there any possibility that your evaporator is icing up? If you turn off the AC for a few minuets and put it on Vent will it start blowing air again?
Jim

 

I have the same symptoms as HarleyHauler and I now believe it is the evaporator icing up. It happens when there is high humidity and when I have the A/C set on very cold but the blower turned down (my wife likes it like that). When it happens, I turn off the A/C and turn up the blower. After a few minutes, the air will start moving again and it is cold. After another few minutes the air flow really increases but it is now warm air. I can then turn the A/C back on and it operates normally.

What I don't know is why it has now started to do this. In four and a half years, it did it once last summer but now did it a half dozen times this past month on a trip to Colorado. The drain seams to be working as there is a puddle of water under the truck when you park it.

Any ideas?

The Boss Hog

 

i would think it is the blendor motor.... simple problem but pricey

 

Sounds like you guys are low on freon

 

Thanks for the feedback. I had a slight dripping inside the cab on the passenger side (asme thing I had years ago in a POS Suburban). It sounds like the condensor icing up is this issue, but the question always comes back to Why?!

Low freon may be a possibility, but it blows colder than winter in Minnesota! Maybe the temperature differential and humidity level made for a bad condition.

Hopefully this won't be a problem on the way to Southern Texas this weekend - - momma won't be happy!

Thanks again gents!

 

its your freeze switch ether the capilary tube is in the wrong spot or the switch needs adjusting or replacing 058hamer

 

058hamer is thinking what I am thinking. It's called a thermal expansion valve. Some cars use a orifice tube and others use a txv. They both do the same thing basically. The txv however has a dip tube, as mentioned above and it is stuck through the fins of the evap. It's supposed to kick off the compressor or open, something of that nature, basically it's supposed to keep the evap from freezing. On the cadillacs we had sensors all over the place that took care of that problem and the caddy's also used an orifice tube. To replace the txv.....you better get your hip waders on cause you have to go deep.

If you have water dripping into the cab area around where the hvac case is, around the passenger foot area you may crawl under the truck and find the hvac case drain and clean it and make sure the passage is open. We had a couple cars, again at the caddy dealer that would have over a gallon of water in the case and make a horrible mess of the carpet. I usually used a coat hanger. Most of the ones I have seen have a rubber tube that will come off. The caddy's had a weird shape at the end, instead of being just a round drain they had a crimped end with a small slit and this slit would stick together and then you had your very own mobile pond. I would cut the slit off so it was open.

As far as the txv, it's been a long time since I worked on the dodge a/c so I'm not to sure if you can use a scan tool on yours to see the evap temp. Other than just throwing a new txv on it that is the only thing I can think of to check it.

Shawn

 

058hamer and Shawn -

Thanks for the info. I will check the HVAC case drain in the a.m. and see if that changes anything (don't need a fish pond in the truck!). I will monitor the AC activity over the next week (a long drive and plenty of opportunity for it to show it's problems, if any) and then take action on the TXV.

Thanks again, you folks have been terrific!

 

HarleyHauler,
Were you able to find a solution to your problem? I am suffering from the EXACT same thing, cold/warm/no/cold air, dripping on passenger side, the works, just like you described.

As you kindly put it "Momma" and I just finished a trip to Texas from South Florida...the AC issue was NOT fun...

It would be great if what you tried resolved the issue!

 

Just a small suggestion for all you guys. What I do is go to the parts store and buy one of those small thermometers and keep it in the center vent on my truck year round. When it's time to use the a/c I check the temp out the vent occasionally and monitor it's performance. The other day it was on max a/c and 75 degrees was all it would put out. It was better to have the windows open.

Checked my a/c system pressures, shot a half a can of 134 in it and got the pressures up to where they should be, vent temps went down to 45 degrees. Probably a small leak somewhere. I checked all the lines, used my high dollar leak detector with nothing found. If you have to add freon use the freon with the UV dye in it. This is especially good on difficult leaks. Then after driving for some time you can use a UV light and check over all connections, sensors etc for the dye. Also look for oily spots around connections, dark spots on the condensor that look out of place as compared with the rest of the condensor, usually indicates a leak.

Best thing to do is check system pressures. The ambient temp(outside temp) will vary pressures on the high and low sides. In theory there should be a 20 degree temp difference between ambient and outside temp. Most of the time in my experience a good system will run 40-50 degrees out your vents in the hottest weather and humidity. If you hook up gauges to check pressures you should see around 250psi on the high side and around 30psi on the low side. Like I said it can vary depending on ambient temperature but this is a good rule of thumb to go by. Also if you have good high side pressures and high low side there is a problem internally. Feeling the lines is another good way to check the system. The small line off the compressor should be hot, hot going into the condensor, hot coming out of the condesor. It will get cool once it runs through the thermal expansion valve. If it's hot going into the condensor and cold coming out of the condensor there is a restriction(orifice) in the condensor.

Well hope this info helps, if you have any questions feel free to email me and I'll help out as much as I can. Kinda hard to troubleshoot over the internet so as much information and observations that you make help.

Shawn

 

when a system first starts to get low on refrigerant, it will run too cold and ice up. lose too much refrigerant and pressure sensors will not allow compressor to run.

some vehicles have a TXV or thermal expansion valve. others use a fixed orifice to meter refrigerant. best way to make sure correct amount of refrigerant is to pump it empty. then dispense correct charge amount from vacuum.

 

I do not have a newer truck but my son had a 2002 Ram and now a 2006 Hemi and he had a problem with the 02's AC. When he would turn a corner you could hear water rushing back and forth inside the dash.
Anyway he took it back to the dealer and after a runaround it was repaired but I remember when I was checking for TSB's there was one about the evaporator freezing up and cycling switch, the service bulletin was for the dealer to relocate the insertion point of the bulb on the cap tube to a different place on the evaporator.
I have tried to go back and find the TSB I was reading but I have not had any luck finding it, I was just browsing through then and do not remember the number.

Does the AC report anything back to the ECM as far as diagnostic codes?
Jim

 

Thanks again to all of you who have offered assistance. Here is an update on the condition as I have returned from my vacation.

The air would blow colder while at lower speeds, warmer at highway speeds. In addition, the air blew colder on the driver's side of the cab and warmer with less airflow from the passenger's side (I am glad that I was driving!).

From this performance, I am thinking I may have two potential problems: the blender (side to side differences) and potentially the coolant level. I think that my best solution path at this point is (unfortunately) to head to the dealer for assessment and correction. Momma was adamant about getting it fixed before the next trip!

However, the trip was great, we had fun on the beach (got to use the new power upgrades) and got better MPG's to boot.

 

I've had the same issue with my 2003. After awhile of driving the evapor would freeze up. Took it back to the dealer. It ended up being low on freon do to a small leak in the system. they fixed it, and it has been working great since.

steve