Model: PT Cruiser
Engine Size: 2.4 Turb
Refrigerant Type: 134a
Ambient Temp: 90
Pressure Low: 65
Pressure High: 480
Country of Origin: United States
Helping a friend here and would love some ideas. They mentioned their a/c wasn't working so I connected my gauges today. When first connected they both read right at 110/120. At idle the high side reads around 270, low side around 65 and the vent temperature gets to 70.6 . Ambient temperature was around 90 with 65% humidity. Controls set to max with recirc. on and windows up. I ran the rpms up to around 2000 and the high side rose to around 470-500 and the low side stayed around 65. I am guessing a high pressure cut off was doing its job because after about 15 seconds of that high pressure the compressor would cut off, the high side would go back down to below 250 and the low side would climb up to 70something then the process would start over.
Tomorrow I will make sure the fans are running and mist the condenser to see if there is any change but in case anyone is bored tonight and has more ideas I'd love to hear them. Another thing of note, when I connected the low side I could see some green dye as the valve purged. Factory use green dye or has someone been in there?
Looking in a chart I found it says at 90F ambient temperature the acceptable range for outlet temperature is 60-76F with a high side between 280-300 and a low side of 45-64.
I told them I felt they should take it somewhere to have it evacuated, checked and refilled back to spec and go from there but I want to know why I am seeing what I see.
Keep in mind, I'm just a guy that likes to figure stuff out, I don't do this every day. (I still haven't finished my first project with the R12 Camaro). I don't know much of what I am doing but I love to read and learn. Thanks!
It is essential that the condenser fan works. The other strong possibility is overcharging, you need to ask the owner if anyone has tried to charge it lately. Check the static pressure in the morning when the car is completely cold and compare to pressure / temperature chart. If static pressure is higher than the chart indicates, that's likely air contamination.
you hit it right on the head with the condenser fan. I checked static pressure this morning like you asked and found a chart. Pressure was ok with temp. I bypassed the relay, high speed fan came on, low side dropped to 45 and vent temps came down to 50.
I didn't hook up high side again since it took me about an hour yesterday and my arm is still killing me from the shape I had to bend into to hook it up. I feel like the problem is solved and I helped them out with help from this great forum!
(My first guess was that when the a/c stopped blowing cold air the current owner put one of those quick fill up things of r134 in there and it was now overcharged....thankfully I was wrong)
The static pressure isn't affected by a under or over charged system.
didn't mean to cause any confusion and if I need to hook up the high side again i will......maybe not today but soon after my arm isn't sore. (I will hook it up because I want to learn and I am curious as to what it reads now)
wptski - thanks but i don't even know enough to draw those conclusions :-) . All I know is the high speed condenser fan wasn't working before but I didn't know it. I think i understood the part about checking the static pressure, if I am right if there was something else in the system besides r134 (air perhaps) then the pressure would be off? The compressor seems ALOT happier now. They asked me to go ahead and get a relay for them so I will report back when I do and when I check all pressures again if y'all want.
no worries on my end........I'm bummed again though because I started testing the relay and I'm pretty sure the relay is fine. I reinstalled it and turned everything on again. This time I hear the high speed fan start but I am back where I started with low side pressure and outlet temperature and compressor being unhappy. I removed the relay, jumped the connection but nothing changed - high speed fan starts but low side pressure remains 65 and outlet temp is back to upper 60's.
now it is raining so i will wait until tomorrow and start over - hook the gauges back up both high side and low side and go from there. Just when I think I have a grasp on things ......
alright, its morning - now afternoon. I went out this morning and took static pressure at around 90 low side and 98 high side. The temperature is 87ish with around 70% humidity. I started the car, turned the ac and fan on high with recirc on. At idle the low side is at 65 and the high side is around 280. At 2000 rpms the low side stays around 60 and the high side shoots up to around 475. Vent temps are in the low 70's to upper 60's. The high speed fan turns on and is running. I misted water on the condenser as it was running with no change in pressures or temperature.
It seems not only have I started over, I have gone backwards? Which way to look now?
I took a video of what I am seeing as well as some temperature measurements with an IR thermometer. The video is awaiting upload to my photobucket if that will be helpful. Another thing that migh come into play is a 'loud belt'. The car has a belt, the belt that drives the a/c compressor that is squeaky. I can squirt a dab of wd-40 on the belt and it will quiet down (don't have any belt dressing). That is how I narrowed it down to that belt. I am going to leave the gauges hooked up in case anyone has anything else for me to try or look at. Its just strange to me that it worked fine that one time.
I'm taking a break. I'm sure I am overthinking and missing something I should see. So this morning I go out and check my readings. Ambient temperature around 82, static pressure near 95 on both sides. I crank the car and turn the a/c and fan on speed 3 (not 4 high as I have been). At idle, the low side goes to 48, high side 225 and the vent temps are around 56. I turn the fan speed on high and the low side goes up to 60, the high side to 280 and the vent temperature around 67. I turn the fan speed back to 3 and the high side goes down to 250 and the low side in the low 50's. When I raise the rpms to 2000 the high side will rise to 375 up to 425 and the low will stay in the 50's. I did this routine a couple times then took a small break. I went back out and now at idle the high side is 300 and the low side is at 60. High side will rise with rpms but the pressures don't go any lower than that.
I found a 'charge determination chart' and took a high side line temperature reading of around 138. At that time my pressures were 300/60. Looking at the chart it says the system has the 'proper charge'.
Any ideas from here? (besides tell them to take it to someone that knows what they are doing)
the reason why your vent temps increase on high blower is because the air is blowing thru the evap qicker than on lower speeds. At lower speeds, the airflow is less so the air has a chance to be in contact with the evap longer. What happens if your rpm is at 1500, doors open, and you mist a water hose on the condenser? If the high side drops like a rock as I think it will, you have an airflow problem across the condenser. You can place a fan in front of the grill to aid the vehicle fans.
Ok, the vent temp thing makes sense. I went out and tried again....best result yet - just as you predicted. I started it up and the low side settled at 50 and high side around 340. Ambient temps still 82. I sprayed the condenser with water, rpms 1500, windows down and yes it dropped like a rock. I guess the last time I did that I wasn't using enough water. Low side got down to 35 and the high got down to 250 with a vent temperature of 44.
I did hear the high speed fan turn on when I turned on the a/c. I will look harder for an airflow problem, dirty condenser fins, something. I guess I should mention too - I can't road test it because they towed it to me to do other work to the car and it isn't insured and doesn't have a tag on it. Thanks again for the help as I seem to be my own worst enemy so far in this. Sure is good education though.
make sure the fan is turning in the correct rotation.
I took the grill off the car. The fan is turning in the correct direction (blowing air toward the engine) and the condenser looks pretty clean. I'll clean it anyway. I did notice one of the air shields, the one on the driver side was missing and the one on the passenger side was torn right there where the high side connection is.
Temperature is 80 right now, its dark, I checked the pressures and high side was around 175, low side around 38 and the air was pretty cold (didn't have my thermometer out there). Hopefully I will have time to work on it tomorrow afternoon and will update when I do. Thanks again!!
It is acting like it is overcharged. Are you sure that it is not?
Nope, not sure at all. I asked them if they added anything to it or if anyone has been in the system and so far I've gotten a no or no idea. The car was in a small front end collision but none of the a/c system looks new. I read in the sevice manual that the factory does put dye in the system so that answered that question I had earlier. I am going to look close and probably replace that belt that is noisy, clean the coil, figure something out for the air shield and past that it is a little past my ability to do much more at home I guess. I did notice an unplugged connection in front of the radiator which I found is supposed to go to an ambient air temperature sensor. I though 'ah ha' but it turns out, the best I can find, that there are two of them on this car. One feeds the PCM (which is there) and one feeds the overhead thermometer reading (car doesn't have one therefore no sensor for it). Also seems the turbo 2.4L has a variable speed radiator/condenser fan - not just high and low but there is a big difference now between fan speed having the a/c on and not so I guess that is ok now.
Thanks everyone for hanging in there with me.
So I cleaned the condenser with cleaner (Alka-Brite +) then rinsed it. I fabbed up some air shields for the sides of the condender/radiator area. I started the car and a/c and the pressure was 40 low and 185 high. It stayed like that for a couple of minutes blowing air in the upper 40's. I ran it up to 1500 rpms and held it. The low side went up to 50, the high side went up to 325 quickly then shot back town to 225 then crept up to 260. The vent temperature was around the low 50's. I let it idle again and the high side went down to 250. I hosed the condenser with water and the high side went down to 200 and the low side down to 45ish. Vent temps remained in the low 50's. I think I have done alI can do unless anyone has other ideas. I would love to know the amount of refrigerant in the system as it seems that is the only thing I haven't verified at this point.
I did find it somewhat strange there was no belt noise today.
We've updated our forums!
Click here to visit the new forum
Copyright © 2016 Arizona Mobile Air Inc.