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Poor ac cooling as ambient temperature increases


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I live in an area (deep south Texas) that's just hot and humid, ac is a must. 
 
My ac use to blow 45 degree or colder air no matter the temperature humidity outside, recently the ac performance began to degrade. As the ambient temperature increases so does the temperature of the air coming out of the ac. On a day in the 90's temperature of the air coming out of the center vent (temp readings done with max ac, fan on high, center duct) would run from 55-65 and humid air.
 
The ac system is still all original parts from 2002, other than being recharged 2 years ago at the dodge dealer and few weeks ago.
 
After putting gauges on here is the basic findings (center vent temp is about 55-65): 
 
Static pressure is same both sides (100 psi)
 
At idle Low Side 40-55, High Side: 200-350 (ambient Temp, 84-95). The high side does show “spikes”  occasionally, sometimes they are rapid spikes meaning a jump on high side of 50-100+ (low side stays the same as I recall, might go up a bit), then high side drops to previous psi reading, sometimes the high side will start say at 200, then gradually go up does not come down, low side will go up as well, not sure if that means anything ?
 
At 1500-2000 rpm Low side 35-40, high side 200-250 (both sides steady pressure, no spikes etc.)
 
Other findings:
 
The condenser seems to have a the same temperature (running my hand across condenser), anywhere I place my hand. Dryer / Accumulator seems to have good sweating, high side to me should feel “hotter”.
 
When using the gauges I recover some r134a, in the sight glass the color was reddish / brown, is this normal ?
 
Once in awhile (mainly when ambient temperature is 95+) when the ac compressor first starts, you can hear it strain , the belt does slip a bit on the compressor pulley when this happens. Overcharged system ? I evacuated enough freon to start short cycling (thinking overcharged), then added back 1 120z can. This seems to have stopped the “hard start” as I call it, seems to cool just a tad better. Can't test for a hot day as cold front came threw last night.
 
Could I have a blockage (orifice or dryer/accumulator), evaporator plugged with years of dirt, ac flush needed, to much ac oil ??
 
Thanks for any help  :)
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When using the gauges I recover some r134a, in the sight glass the color was reddish / brown, is this normal ?

 

No. It's not normal. I gather you got moisture in the system and the orifice tube is most likely starting to plug up. I'm going to assume there is other damage occuring too. Truly the freon should be clear in color or possibly yellowish from possibly a dye pack added. But reddish brown sounds like rusting has occured.

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I agree about the orifice possibly plugging up. The condenser should get cooler the farther down you feel. If it seems to be the same temperature that means either the system is empty ( obviously not the case) or there is refrigerant backing up and staying in the condenser. However, another problem to consider is the evaporator plugging and not allowing the air to flow through the whole coil.

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I agree about the orifice possibly plugging up. The condenser should get cooler the farther down you feel. If it seems to be the same temperature that means either the system is empty ( obviously not the case) or there is refrigerant backing up and staying in the condenser. However, another problem to consider is the evaporator plugging and not allowing the air to flow through the whole coil.

 

 

No. It's not normal. I gather you got moisture in the system and the orifice tube is most likely starting to plug up. I'm going to assume there is other damage occuring too. Truly the freon should be clear in color or possibly yellowish from possibly a dye pack added. But reddish brown sounds like rusting has occured.

 

Moisture in the system would be from a leak ? 

 

The evaporator I can't get to easily, so I would look for leaks, repair as needed, flush entire system remove lines flush, remove condenser flush, evaporator flush best I can still in truck, replace orifice, dryer, evacuate, recharge, or screw it take whole thing apart hmm.

 

After doing all that only other possible problem area would be compressor and/or evaporator, trying to follow path with least cost, and tear down (if it's not broke don't fix it lol) for now. If after all that still does not work then has to be evaporator.

 

For those that have removed the HVAC how bad a job is it, I consider myself intermediate in terms of abilities to tear stuff up and put back together.

 

Condenser gets cooler as you go down, how cool ?

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Moisture in the system would be from a leak ?

 

Typically from opening the system and then refilling with freon with putting a vacuum on it to boil the moisture out.

 

I would replace the accumulator and orifice tube.  Pull the compressor and dump the oil out and reload with new fresh clean PAG oil. (7.1 ozs - IIRC) flush the rest of the system with AC flush.

 

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Typically from opening the system and then refilling with freon with putting a vacuum on it to boil the moisture out.

 

 

 

System has never been opened that I'm aware of, Dodge dealer added freon while back.

Edited by tonyjsan
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The line from the compressor to the condenser is a high pressure vapor line that can and does get so hot it will burn you (I have received blisters from it). The condenser will be the hottest on top and then be about ambient by about 2/3 to 3/4 of the the way to the bottom. Does the suction line get "beer can cold"? If the evaporator is dirty the suction line should actually get so cold it can ice up on the outside. You say you removed some refrigerant thinking it was over charged. How did it get over charged if the last time it was serviced was two years ago? It is possible that since you removed some refrigerant it may be under charged.

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Reddish brown  makes me think there is  a ton of  stop-leak  type crap  in your system.   Not so sure on the  rusting...  not very much ferrous iron in these  systems.  I think the  pistons in the pump are even  stainless..

You've said  it's been serviced a few times  in the past..and probably been subject to  various  'recipes' of  instant fix..  Probably time to  flush the whole shebang,  replace the  receiver dryer and  expansion tube...  and  draw the whole thing down.

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The line from the compressor to the condenser is a high pressure vapor line that can and does get so hot it will burn you (I have received blisters from it). The condenser will be the hottest on top and then be about ambient by about 2/3 to 3/4 of the the way to the bottom. Does the suction line get "beer can cold"? If the evaporator is dirty the suction line should actually get so cold it can ice up on the outside. You say you removed some refrigerant thinking it was over charged. How did it get over charged if the last time it was serviced was two years ago? It is possible that since you removed some refrigerant it may be under charged.

 

So far no icing up there is "sweating" seems like there could be more. I'll have to try the high side line to see how hot it is, that's what I was thinking the high side will burn. As for the re-charge another was done few weeks ago (thinking it needed more due to the poor cooling) I added a 14 oz can of freon (12) / oil (2), after that I started getting the "hard start" on the compressor as I call it, so figure I had overcharged it. I evacuated enough to get the compressor to short cycle then added back 1 12oz can. At this point it's not gotten warm enough to test it for sure, today at lunch with 80 ambient temp, center vent was 45, however humidity today 25% (very low for here), the other day humidity was 90%+

Edited by tonyjsan
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does it start out  cold,  and  fizzle out?  or  is  it  the same  all the time?

make  sure your  hot air door  is  shutting

see if  you are  icing up the evap,  your  statement on  the  high humidity/low humidity  difference in cooling  makes me wonder about that!

I'd  still consider a  r/d  and  tube  change out,  and  flush,  the color isn't  good!

I swear,  some  AC shops  will  'add' crap  just to have repeat business...   their  fix  helps  short term,  but  you will be BACK in a few weeks!

Edited by rancherman
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does it start out  cold,  and  fizzle out?  or  is  it  the same  all the time?

make  sure your  hot air door  is  shutting

see if  you are  icing up the evap,  your  statement on  the  high humidity/low humidity  difference in cooling  makes me wonder about that!

I'd  still consider a  r/d  and  tube  change out,  and  flush,  the color isn't  good!

I swear,  some  AC shops  will  'add' crap  just to have repeat business...   their  fix  helps  short term,  but  you will be BACK in a few weeks!

 

it was starting out say 55, as ambient temp goes up air coming out gets warmer. Today it seems fine (45 degree air out vent) but again it's 80 out 25% humidity, I need for the south texas heat to crank up again, cold front this late is rare. 

 

I do believe I am for sure going to do the flush and change out the orifice tube and r/d, what I'm debating is to remove the hvac box, aside from ac, i believe my heater core might have a small leak of some sort, as I can smell anti-freeze via vents when temp knob on full hot. It's been that way for awhile, and I've not notice any major coolant loss.

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well,  now's the time to kill 2 birds  with one stone!    (heater core and  evap!)  You sure don't want to do this  twice!!

I've  seen  some real nasty  coating of  slime/algae/disgusting  snot  growing  in  high humidity evaps!  OH GEEZ... I just about forgot to ask!!!

 

IS YOUR  DRAIN TUBE BLOCKED????

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well,  now's the time to kill 2 birds  with one stone!    (heater core and  evap!)  You sure don't want to do this  twice!!

I've  seen  some real nasty  coating of  slime/algae/disgusting  snot  growing  in  high humidity evaps!  OH GEEZ... I just about forgot to ask!!!

 

IS YOUR  DRAIN TUBE BLOCKED????

 

lol yech !!!!!!!!!!!

 

Yep drain tube I believe is ok as there is a nice puddle of water when I stop the truck turn off engine.  :thumb1:

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  • 3 weeks later...

 

I would replace the accumulator and orifice tube.  Pull the compressor and dump the oil out and reload with new fresh clean PAG oil. (7.1 ozs - IIRC) flush the rest of the system with AC flush

 

Finally got around to working on the ac. Decided not to mess with evaporator for now. AC system seems to be working good 43-45 ambient temp of 80, low humidity, real test will be as it get hotter and more humidity.

 

I did run into a few gotchas, the orfice tube I found is not replacable (deigned to not be replacable), so I just replaced the entire liquid line, the suction / discharge line was replaced as well, this was a dealer only item and was spendy, local auto stores did not carry but found out after ordeing that I can get it from napa, or online.

 

Removed the compressor the oil that came out was not clear a strange redish to orange color, reminded me of leak locate stuff if it was the dealer added that, I dumped all the oil then added some drained, until oil came out clear.

 

Flushed the evaporator and condensor. During flushing the evaporator seemed to build up a little preasure beforre all the ac flush fluid came out.

 

Then of course but it all back together.

 

I did have one question label under truck says something like 1.8xx lbs freon, which if I did the math correct is 30oz, I added 3 12oz cans, the extra 6oz will not overcharge, at this point I did not worry about it as low/high side preasures and temp from center vent within specs.

 

Second since I added 7 oz of oil, direct to compressor, should I have added an oil charge like 2oz can ? I did not.

 

one final thought before doing all this the high preassure side was jumping to 450+ at 2k rpms or less so blocked for sure

 

Thanks everyone for the help :)

Edited by tonyjsan
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  • 4 weeks later...

I'd like to ask for some help again, after all the repairs descriped in a previous post, I still have the same issue, if anything the ac is now worse than before. Let me recap all the work done over month or so.

 

Replace dryer, liquid line, suction line, flushed evaporator and condensor with ac flush. evacuate and charged system would cool to 65-60 in town 45 on highway. Before charging I let system set for 1-2 hours vaccum held at 30in.

 

With the poor cooling at higher ambient temps, I decided to change the compressor out (seemed like low side not sucking enough). Evacuate charged, poor cooling, took it to the dealer they checked charged said I overcharged it they brought it to specs, still has same issue cools to 75-60 in town, highway a bit better.  again i let system hold vaccum for hour or so held at 30inches.

 

I did not change the dryer when installing the new compressor, seems to me for that short time would not effect dryer.

 

So any ideas whats wrong ??

 

Is there a leak ? Evaporter plugged meaning restriced air flow over evap, is there away to test for restricted airflow ?, condensor is clean leak there ?

 

Does the system not leaking vaccum mean no leak for sure ?

 

Perhaps time to take to the dealer but they are so spendy

 

Thanks in advance

 

Tony 

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Man,  you've  pulled some nice numbers  on your pull down...  It's hard to believe you may have a leak!  

Is your  condenser  pretty good shape?  ( fins  clean,  not  all  smashed)   do you hear your   cooling fan on all the time?    When  mine   engages a lot, ,  I know it's time to   blow out  the radiator/intercooler/condenser

 

you  say it's   a tad better  at  hwy speed,    which  makes me wonder now if  the condenser isn't  getting  enough air,  and  you may  be  getting  high  intake pressure,  causing  the compressor to shut off.    There is  a low  pressure,  and  high pressure  cut out.

Can you hear it  clicking  in and out?

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Mine always starts out a bit warm sided but after few miles and giving it time on low setting it cools down good (40-45*F) from the center vents and then I crank up the fan speed and push the cold into the cab. With high humidity you'll want to run more MAX A/C than normal.

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Man,  you've  pulled some nice numbers  on your pull down...  It's hard to believe you may have a leak!  

Is your  condenser  pretty good shape?  ( fins  clean,  not  all  smashed)   do you hear your   cooling fan on all the time?    When  mine   engages a lot, ,  I know it's time to   blow out  the radiator/intercooler/condenser

 

you  say it's   a tad better  at  hwy speed,    which  makes me wonder now if  the condenser isn't  getting  enough air,  and  you may  be  getting  high  intake pressure,  causing  the compressor to shut off.    There is  a low  pressure,  and  high pressure  cut out.

Can you hear it  clicking  in and out?

 

The condensor fins are in good shape a few areas where they are bent, i'd sa maybe 1-2% of the condensor surface area is bent. Visual insection shows no dirt etc, front of condensor is gray / dulled aluminum look the back is bright new aluminum look.

 

I put the gagues back on this morning outside temp 84 humidiy 50-70%, with fan clutch engage, low side pulled down to 30-35 high to 180-200. I rev rpms to 1000-1200 all look good. After the fan clutch disengaged I reved to 1000-1200, ok for a little bit then the high side climbed to over 350, and low side climbed as well. Shut ac off after it hit 400 and still climbing at idle. Then after system equalized started ac, low pulled down ok and high climbed ok at first, then high went past 350, this time I litly sprayed condenser with water of course high side dropped and low side. Not sure if the findings above mean anything or not.

 

I wanted to see if there was airflow across the condenser, a klenix tissue was sucked tight to the condensor, again not sure if that means air flow good  / bad.

 

Fan clutch is brand new. is it possiable for a condensor to loose ability to give up heat as it ages ?

 

Mine always starts out a bit warm sided but after few miles and giving it time on low setting it cools down good (40-45*F) from the center vents and then I crank up the fan speed and push the cold into the cab. With high humidity you'll want to run more MAX A/C than normal.

 

That is the behaviour when my ac system was working.

 

Orifice tube are super easy to replace. I know I know with your limited function you not capable dang I really do wish sometimes I was closer to help you out.

 

On mine the oriface tube is a pain, it's by designe not replacable, I have to cut out the old oriffice, install a orrice repair kit basically a small piece metal with compressionn fittings inserted where oriffice tube was installed

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