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Clemsonfor

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Ok I know it's not saws or outdoor related but I know there a lot of guys on here that are mechanics and know it.

I have a 2004 Sequoia. It has Freon in it. It will blow cool, I don't have a dial thermometer but it might get into the low 70s after a good long drive. Sitting does not cool well at all and in the last year there has been a handful of times it went to blow warm then back cool. Last year I sucked freon out, it was dead on I added back the proper amount. At that time pressures were all within spec.

Yesterday I hook gauges up. Low side was around 50-55psi and didn't move unless reved to like 2000rpm it would climb to like 60. The H side was at 50 and wouldn't move. Again I don't think its freon but I grab the tank and added three slow bursts of a few seconds to it and neither pressure climbed at all telling me it's not a low freon issue.
Edit: Air temperature outside was say 93f or so.
I have a few thoughts and what my first thought was but I want to hear what y'all say.


Soooo go!

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thedude74

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If your hi side and low side are both at 50 psi the compressor either isn't running(see if compressor clutch is engaging) or has some serious internal damage.

Sure your hooked up to the low and high side? There should be a large differential in pressure with the AC running.

If the low side is in the 50-60 psi range while the AC is running your most likely overcharged on refrigerant. Should be around 35-40 psi at idle with the fan on high, doors and windows closed, set to recirculate.
If it's overcharged what's happening is the high pressure switch is opening and cutting off the compressor until the pressure drops... especially at driving speeds vs idle.

50 psi corresponds to 54 deg. F and 60 psi corresponds to 62 deg F.

Possible there is another issue. But this is where I would start.

Disclaimer: I'm not an auto mechanic but I did stay at a Holiday Inn last night!

Seriously though. I've been an HVAC tech for three decades.
 
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Clemsonfor

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If your hi side and low side are both at 50 psi the compressor either isn't running(see if compressor clutch is engaging) or has some serious internal damage.

Sure your hooked up to the low and high side? There should be a large differential in pressure with the AC running.

If the low side is in the 50-60 psi range while the AC is running your most likely overcharged on refrigerant. Should be around 35-40 psi at idle with the fan on high, doors and windows closed, set to recirculate.
If it's overcharged what's happening is the high pressure switch is opening and cutting off the compressor until the pressure drops... especially at driving speeds vs idle.

50 psi corresponds to 54 deg. F and 60 psi corresponds to 62 deg F.

Possible there is another issue. But this is where I would start.

Disclaimer: I'm not an auto mechanic but I did stay at a Holiday Inn last night!

Seriously though. I've been an HVAC tech for three decades.
What your saying is what I was thinking. It's not 54 outside but more like 93 when I checked.

As for gauges, you can't hook them up backwards on an auto at least there sized different, but even if not I know H is red and L is blue.

I know what pressures I should be seeing as well. When I charged it last time when I had cooling issues I pulled it all out cause I wondered if it was low. The exact amount was inside and I out back the correct amount to the ounce.

Clutch is engaged and turning.

Your suspecions are what I had come to as well.

I forgot to look or if I did I don't remember what the static pressures were but I agree they should be higher than that.

Thanks for your input. I was about to order a compressor yesterday but got side tracked. I will today.

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Lightning Performance

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Check all the flow paths in the system before replacing the compressor. If you have an orifice valve it may be clogged or the disicant dryer may be clogged. Replace both and check those before you install a new compressor.

Edit: I have stayed at a Holiday Inn but never an Express so I may not be qualified
 

Clemsonfor

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Check all the flow paths in the system before replacing the compressor. If you have an orifice valve it may be clogged or the disicant dryer may be clogged. Replace both and check those before you install a new compressor.

Edit: I have stayed at a Holiday Inn but never an Express so I may not be qualified
Here is my thought process. It does have an expansion valve. Dash has to be torn out to change it so it's the last choice. But where the H reading is taken the flow comes out of compressor, through condenser and then dryer than H service ports then the line to the valve and evaporator. So the only place a restriction would make sense would be in the dryer or condenser right? If the pressure reduction was at the expansion valve (which there could still be one) I should still be getting a higher H reading than I am getting because I would have full flow up to that point.

I need to take my IR gun and take temp readings all along the lines from compressor to the H port to see if I have a temp difference and a restriction.

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Lightning Performance

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Here is my thought process. It does have an expansion valve. Dash has to be torn out to change it so it's the last choice. But where the H reading is taken the flow comes out of compressor, through condenser and then dryer than H service ports then the line to the valve and evaporator. So the only place a restriction would make sense would be in the dryer or condenser right? If the pressure reduction was at the expansion valve (which there could still be one) I should still be getting a higher H reading than I am getting because I would have full flow up to that point.

I need to take my IR gun and take temp readings all along the lines from compressor to the H port to see if I have a temp difference and a restriction.

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Yeah....I'd say your compressor is toast if you have no pressure spikes but once in a while they clog on the pickup side and make no pressure at idol.
 

Larry B

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Sounds like compressor is toast. If you replace it you need to replace the orifice valve and any seceen or filter in the system and flush the entire system with the proper solvent to make sure system is clean of any debris from the compressor. If uou don't and just change the compressor and recharge it will fail again soon. Look for a kit to replace compressor and needed parrs.
 
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thedude74

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Sounds like you got it figured out. With a restriction in the refrigerant system you would see a lower than normal low side pressure due to lack of refrigerant returning....which your not seeing. And of coarse the compressor would be cutting in and out due to the low pressure switch opening and closing.

I remember the first compressor I diagnosed that had a sheared motor shaft(240v hermetically sealed residential). As you can imagine the pressures didn't change at all even though my amp meter confirmed the compressor was running. Had me scratching my head for a minute as a broken shaft was fairly rare.

The fact that you're getting some difference between low and high leads me to believe there is major damage to the compressor valves.

Those IR laser thermometers sure are handy tools to have aren't they?
 
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FergusonTO35

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All good advice here. Given that the thing is a 2004, you may want to consider replacing everything AC related that can be replaced. It is not as expensive or difficult as it sounds, I did my daily driver for around $500.00 using decent aftermarket parts from Fleabay.
 
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