A/C expansion valve??

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john188971
Posts: 34
Joined: Mon Mar 21, 2016 4:05 pm

A/C expansion valve??

Post by john188971 »

Good morning all!
I've been having troubles with my ac in my 2006 vibe. Currently has 80k on it.
I've posted a couple threads with no reply. Now I have a bit more information to give.
Symtoms;
With the ac on after driving for a while the vents will stop blowing. Shut ac off and maybe 3 minutes later I will get air movement out of the vents. But it's @22 degrees. And after 10 minutes or so air stops again.
This has been happening all summer.
Now it'd getting cooler outside (Chicago area)
So defroster is needed.
Same thing stops blowing after maybe 20 minutes of driving. Turn to vent, ac off, and @3 minutes later I start to feel air.
So finally I got time to take it to my buddies shop. This is what we found:

Low side starts freezing almost immediately. Gets really cold and then the frost starts forming. From the ac compressor all the way to the fire wall.
High side won't go over 50 psi
Low side maintains 35psi.

So my buddy thought of orifice tube... Too bad the vibe doesn't have an orifice tube!
Now it's pointing to the expansion valve.
Cheep part. But where the heck is it?
Does the whole dash have to come out?
I cannot find any documentation on replacement or even location! :o
Can anyone help? Any suggestions? Am I missing something?
Thanks for everyone's time
Owim
Posts: 46
Joined: Mon Apr 28, 2014 3:57 pm

Re: A/C expansion valve??

Post by Owim »

I'm no expert but if the air isnt blowing that sounds like the blower motor kinda deal
2009 2.4 AWD
john188971
Posts: 34
Joined: Mon Mar 21, 2016 4:05 pm

Re: A/C expansion valve??

Post by john188971 »

Thank you for your reply. I did leave out the blower motor and resistor being changed when I first started my questioning about this issue back in April or May.
Both the blower motor and resistor are brand new. The fan still blows on all settings I just get nothing out of the fence because the evaporator is frozen solid with ice. If I turn it to vent then after three to five minutes the ice melts enough so I get air out of the vents.
My biggest question is, where is the expansion valve located, and do I have to take the whole dash off?
Since winter is fast approaching I feel it is a safety issue because I cannot run the defroster for very long because it will still iced up even with temp selector on middle or even full heat. I never have a problem if I have it on vent or floor any temperature.
Thanks again for your response
john188971
Posts: 34
Joined: Mon Mar 21, 2016 4:05 pm

Re: A/C expansion valve??

Post by john188971 »

Nothing? No one has any suggestions?
I could really use some guidance on this. Just hate to have to pull the dash out of the vibe!
Especially for a $20 part!
Thanks in advance
tpollauf
Posts: 4027
Joined: Wed Jan 20, 2010 11:37 am
Location: Toledo/Oregon, Port Clinton Ohio
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Re: A/C expansion valve??

Post by tpollauf »

John. I have some time so I'll give you my take on your problem. As a refrigeration mechanic (mainly commercial and industrial) I've messed with my share of cars over the decades. The pressures you indicate tell me TWO things. You either are undercharged OR have a plugged evaporator. The other symptom would be a defective blower motor but you state that the blower is running continuously so we'll rule that out. If you have the tooling here's what I would do. Dump the current charge that you have and start over. Evacuate the system with a good vacuum pump and recharge the car by VOLUME. Most cars take around 24- 30 ounces of r134A. The fact that you are measuring a somewhat steady 35 psig on the suction side baffles me a bit because if you truly were low then it would want to cut out/in from the low pressure control. Also having only a 15 psig differential makes no sense at all. I hope you're not using a cheap set of Harbor Freight gauges :o Try another set for comparison. Robinaire, JB, etc.

In order for the evaporator to freeze, instead of sweat, means your suction pressure must be 28 psig or lower for a good length of time. Perform more tests if possible. Different blower speeds should warrant different pressures. Make sure your indoor cabin filter is clean AND if so make sure the inlet to the evaporator is also clean. If you're not the original owner of the car it is possible that somebody ran it for a long time with no filter and potentially could have plugged the coil inlet.

I'm ruling out the TXV for now as they rarely go bad. Also I have no idea where it would be located on your Vibe. Hope this helps a bit ............. Tim
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2009 Vibe GT (manual), 2009 G8Gt, 2009 Vibe GT (auto)
2014 Silverado, 2004 Vibe GT

"everything is modifiable"
john188971
Posts: 34
Joined: Mon Mar 21, 2016 4:05 pm

Re: A/C expansion valve??

Post by john188971 »

Tim,
Thank you for your advice.
To answer some of your questions.
The gauges are my mechanics and close friend and they are high quality not HF.
As stated earlier the low pressure lines ice up quickly I assume the evaporator freezes up too do to no air flow out of vents. Also when I shut the ac switch off when there no air flow. @5 minutes of the fan blowing the ac drain runs like you turned on a faucet.
If I keep the fan on high with ac on it will take longer to stop the air flow. Unless it's really humid/raining. Then it ices up just as fast.
I am the 2nd owner I bought it in April with 67k.
The first thing I did was change all fluids, engine, trans, antifreeze. Changed cabin filter. And yes it was terribly dirty.
To back up. We tested at all different fan speeds with gauges hooked up. I believe max ac flap is sticking cause switching to max ac doesn't changer fan sound or speed. I know the actuator works on the fresh air but it gets stuck. Doesn't click,
Anyway. No pressure change with different fan speeds.
Previous owner was a heavy smoker. I think the fresh air actuator flap is sticky with smoke!
I had a thought today so I'll run it by you.
Since I'm going to evacuate the system. I thought of disconnecting both lines from the firewall and flushing the evaporator with denatured alcohol.
Thoughts?
Thanksagain for taking your time
John
john188971
Posts: 34
Joined: Mon Mar 21, 2016 4:05 pm

Re: A/C expansion valve??

Post by john188971 »

This morning it was 47 degrees when I left for work. Tuned defroster on full heat medium fan speed. Within 5-7 minutes it was iced up and no air coming out of defrost vents. Turned it to just vent and a couple minutes I had hot air coming out.
I've never seen this before.
My 2009 f150 has a super slow leak in ac. Haven't been able to find the leak.
Needs 1 can of freon a year. When it's low it just doesn't get cold. Never freezes up.
Sometimes the vibe will be @25 degrees out of the vents. Other times @40 degrees
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