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Check your discharge hose above the subframe. This gets clogged and will smell. The smell get into the cabin.
 
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Check your discharge hose above the subframe. This gets clogged and will smell. The smell get into the cabin.
Thanks. I'll try that, but the Toyota agency mechanics made a complete pressure test twice, saying that the pressure in the system is not up to par, and the cause is the compressor. I'm stumped.
 

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Discussion Starter · #23 ·
Be careful touching those tubes especially near the compressor. They can get hot and cause scald injuries.

I'd check the two pipes near the firewall on the passenger side. The thicker one is the return low pressure pipe and the thinner one is the liquid high pressure pipe. The low pressure pipe should be cold (~40F or so) and the high pressure pipe should be warm to very warm depending on the heat load, but still be careful touching it.

Before you do anything, put the manifold gauge on there and read off the pressures at 1500 rpms. If you have a kitchen thermometer, measure the center vent temp on high fan speed and recirc mode. See what the vent temp is. In a normal system, I'd suspect it's just lost some refrigerant over the years and just got to the point where you noticed it.

The earliest year I could find is 2009. For that year Toyota reported a normal leakage rate of 15.5 grams per year. Or about 1/2 oz. I'd estimate you've lost 2021-2004 = 17. 17 / 2 = 8.5 oz. Use that as an upper limit, but if you top off (see Eric's video below), charge a few oz at a time and allow the system to stabilize, don't go all in with the whole can. That can jack up the system fast. The 2009 system holds only 440 grams of refrigerant.

AC leakage rates:

I'm not sure if your model year still has the sightglass to allow you to see refrigerant movement inside the high pressure line. IMO it's a useful tool. And be careful working with refrigerants, it can flash freeze flesh and eyeballs in less than a blink! Search up and read up on safety precautions.

FYI:
I got the manifold gauges on loan and will get the refrigerant soon and check out the system with dye. Also as 75aces said, soap solution on the valves.
 

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Discussion Starter · #24 ·
Does it blow cold when you are driving it at higher speeds? When you are sitting, is that when it doesn't blow cold enough?
It did that sometime back. Now its barely cold at highway speeds.
 

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Discussion Starter · #25 ·
Check the pressure of the freon gas at any A/C repair place. The other thing . . . any odors in the car like chemical smell? That would indicate the A/C evaporator (under the dashboard).
No odors inside the cabin
 

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I got the manifold gauges on loan and will get the refrigerant soon and check out the system with dye. Also as 75aces said, soap solution on the valves.
The dye solution sounds good !!! Soap and water is an old traditional method that works for leaks which my technician used, but couldn't find any leaks top side. So with the inside cabin smell before starting up in the morning, and intermittent cooling after about 10 minutes of driving, it seems that the diagnosis of AC evaporator sounds right. But that's a huge job, about 30 hours of labor. Removing complete dashboard, all gauges, steering wheel housing, etc. etc. etc. and all those little screws and bolts and plastic connections.
Forgot to mention, between $800 to $1,000 cost, including parts and labor. The part is cheap, but the labor . . . .
 

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The dye solution sounds good !!! Soap and water is an old traditional method that works for leaks which my technician used, but couldn't find any leaks top side. So with the inside cabin smell before starting up in the morning, and intermittent cooling after about 10 minutes of driving, it seems that the diagnosis of AC evaporator sounds right. But that's a huge job, about 30 hours of labor. Removing complete dashboard, all gauges, steering wheel housing, etc. etc. etc. and all those little screws and bolts and plastic connections.
Forgot to mention, between $800 to $1,000 cost, including parts and labor. The part is cheap, but the labor . . . .
Sorry to hear that. My Avalon is the same way, but A/C is fine. When I had to pull the evaporator in my '79 Celica, it was a breeze. Six screws to remove the glove compartment, then three screws to undo the duct work. Plenty of room to work. Evaporator was fine, but I had a leak where the two electrical prongs come out of the pressure switch.
 

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Discussion Starter · #28 ·
The dye solution sounds good !!! Soap and water is an old traditional method that works for leaks which my technician used, but couldn't find any leaks top side. So with the inside cabin smell before starting up in the morning, and intermittent cooling after about 10 minutes of driving, it seems that the diagnosis of AC evaporator sounds right. But that's a huge job, about 30 hours of labor. Removing complete dashboard, all gauges, steering wheel housing, etc. etc. etc. and all those little screws and bolts and plastic connections.
Forgot to mention, between $800 to $1,000 cost, including parts and labor. The part is cheap, but the labor . . . .
Surely not 30 hrs !!!!!!! About 1000 or 1200 sounds like the ballpark figure at an indie shop. Just saw a video in fast motion and it looked like a lot of fun (that I can avoid) specially with keeping track of all parts and their respective nuts and bolts.


Planning on doing the project this weekend. If I find the leak under the hood, then a evac, vacuum and refill should be fine or any other parts also need to be replaced?

Anybody have the specs for pressure readings?
 

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If you find a leak then that needs to be fixed. So the first thing is to read out the pressures.

If you use soapy water, then put soapy water around the port caps, not into the valves (or you'll have to use compressed air to blow it out) or risk corrosion there. If the port caps' o-ring seals are bad, then refrigerant can leak out too. The caps are the primary seals.

Low side should be varying around 26-35 at 1500 rpms. High side depends on ambient in the shade, usually around 2.2-2.5x the ambient temperature. For example, at 85F, about 187-212, after the system stabilized for 15 minutes. Again, get the center vent temp in recirc mode too.
 

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Discussion Starter · #30 ·
This is what I did today.

1. Started the car and turned on the A/c in recirc mode. Let it run for about 5 minutes. Sprayed the lines and the ports with soap water. No bubbles observed.

2. Hooked up the guages and checked the pressure at idling speeds - 50/150 psi

3. Reved the engine to about 1500 rpm - 10/135 psi

4. Added a 12 oz can of 134 in initially in larger quantities and then in smaller quantities. Can is empty. When car is idling - 35/150 psi

5. Revved the engine to 1500 rpm - 26/155 psi

6. The adapter on the high pressure line came off with a loud pop. Surprised me as I wasnt expecting it but thinking about it makes sense. This for info anybody else who does AC system pressure check/recharge for the first time.

Ambient temp in shade was 88F. Looks like I need to add some more 134. I will do this tomorrow, giving time for the high pressure side to calm down. At this stage I am hoping to detect the leak with the added dye under the hood. If I find it then replace the component, get the system evacuated at a shop (actually do this before I replace the component), run a vacuum and then recharge the system. If I dont detect the leak then use the car and probably check the pressure every 2-3 months. Keeping my fingers crossed that the dash doesnt have to come off.

Thanks for all the valuable inputs. Like a lot of DIYers, I was very hesitant to touch the AC system but guys gave me the confidence of doing the job.
 

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You may want to consider replacing all the other small seals. Shame to replace a component, only to have to revisit a leak due to a small seal.
 

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If it takes a can to get to those pressures, then most of the refrigerant have probably leaked out. If the system capacity is 440 grams (14.6 oz), then that one can already put you near that. So very slow in your subsequent add and don't go above that limit.

The manifold gauge set might have been an old one without the anti-blowback couplers. As the blowback shouldn't be significant to startle you. I suggest closing off the low side coupler while the AC is RUNNING (this leaves 26-35 psi in the coupler and hose); and SHUTTING off the AC and allow the high side to bleed down before you close off the high side coupler, then remove it. It'll still be higher than low side's 26-35, depending on engine room temperature, but should be lower than the running high pressure. This is why on newer cars I like to use a scan tool to read off pressures (low side indirectly via evaporator temperature) when available.

Of course, there is a way to drain the high side back into the low side (with the can dispenser CLOSED), but that can get tricky so you might not want to do that at this time. Let me try to find a video on that.

Also, you might want to checkout this AC system part of the fixer upper (in various posts of the thread if you browse through), the principle is similar:

 
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