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2001 Chevy Tahoe AC and pressures cannot fix.


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Thinqtanq
Novice

Jun 8, 2020, 8:35 PM

Post #1 of 11 (1348 views)
2001 Chevy Tahoe AC and pressures cannot fix. Sign In

I own a 2001 Chevy Tahoe. This summer I decided it was time to fix my AC. The compressor grenades and it's freaking hot. So I have replaced ever single component in this thing. Compressor, condenser, accumulator, orifice tube, rear expansion valve, evaporator and heater cores. I know it's not necessary to replace all that after a compressor explodes. But thats why I'm here. I have tried everything. I am using a Bluepoint scale along with a Mastercool 69360 to evacuate and charge the system. I have a separate vacuum pump to pull the system into a vacuum. The pump is only capable of pulling 20 hg. But no matter what I replace or try. Once my system is filled to capacity (3lbs due to having both front and rear air. My pressures sit at 70 on the low side and 250-275 on the high side. I have spent 3 days trying to fix this and my soul is crushed any help is most welcome. It's also worth noting the air temperature coming out of the vents is 65-70 as expected with those pressures.


(This post was edited by Thinqtanq on Jun 8, 2020, 9:27 PM)


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jun 9, 2020, 5:15 AM

Post #2 of 11 (1292 views)
Re: 2001 Chevy Tahoe AC and pressures cannot fix. Sign In

The first problem you have is you are overcharging the system. The full charge for that vehicle is 2.7lb.
3.0 is for the Suburban, not the Tahoe.

See what your pressures look like with the proper charge. Do your testing with the rear system turned off.
If you pressures still are too high, then you need to look at the cooling fan and fan clutch.

Make sure when you installed the condenser that it still has seals on the sides so the fan pulls air through the condenser and not around it.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Thinqtanq
Novice

Jun 9, 2020, 9:00 AM

Post #3 of 11 (1286 views)
Re: 2001 Chevy Tahoe AC and pressures cannot fix. Sign In

Will do and will let you know.


Tom Greenleaf
Ultimate Carjunky / Moderator
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Jun 9, 2020, 1:43 PM

Post #4 of 11 (1275 views)
Re: 2001 Chevy Tahoe AC and pressures cannot fix. Sign In

Yup on fan clutch and hunt for a good one. It should about roar if worth a damn reving up just a bit keep up with RPM sitting still is hot enough outside.
Mist condenser (look to hit it with water if coolers for all sorts of things too and that those are clean, low pressure should totally drop off isn't reality just how much shows how bad shedding heat air alone is.
Laugh - it a joke here with hot days and cold back to back just caught it right today to "performance" check out two,


Tom (rear only for pressure on these TX valve in rears will hog bounty and mess you up)



Thinqtanq
Novice

Jun 12, 2020, 7:59 PM

Post #5 of 11 (1231 views)
Re: 2001 Chevy Tahoe AC and pressures cannot fix. Sign In

Ok well I put in 2.7 lbs.and my pressures are 60L and 250H. So that's an improvement. Out of the vent it's 60 degrees as suspected. Not sure if that is satisfactory or not. I was always taught you wanted it to drop to 32L and the compressor then cycles. Well I have never hit that PSI at the right volume. And my compressor NEVER cycles.


Thinqtanq
Novice

Jun 12, 2020, 8:06 PM

Post #6 of 11 (1225 views)
post icon Re: 2001 Chevy Tahoe AC and pressures cannot fix. Sign In

Also Compressor is also noisy. Not like detrimentally noisy. But you can definitely tell when it's running seems like it's louder than it should be.


Thinqtanq
Novice

Jun 12, 2020, 8:16 PM

Post #7 of 11 (1222 views)
Re: 2001 Chevy Tahoe AC and pressures cannot fix. Sign In

I know you're gonna ask. The compressor came with 3oz of oil pre installed. And I added a total of 2 ounces. To account for all the parts that I replaced.


Tom Greenleaf
Ultimate Carjunky / Moderator
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Jun 13, 2020, 3:23 AM

Post #8 of 11 (1211 views)
Re: 2001 Chevy Tahoe AC and pressures cannot fix. Sign In

Just oil and what to expect if thought overdone? Old charts for "Tahoe" only for dual A/C shows 11oz system total of PAG 46! Most GMs used 150 so surprised at that. Note charts can be wrong and say so.


So, with that and if there was oil at all in replacement (unknown really) you should have dumped out that for measuring IMO and either added it back or new with proper oils.


I'm asking now if this compressor has it's own belt behind the other(s) and a pest it's also LOW so just placement a problem for choking on oil should quit or bust best (this one tiny) hopefully if hydro-locked with oil? IDK and can't know.
Known over oil makes erratic performance and if watching outputs while using vehicle in use will splash around and go warm and back as it sloshes along and thru system on curves and altered by hard stops and start up driving!


Bummer you had a chance with all you did to get it exact missed the dealing with new/reman compressor (high risk for failure out of box) didn't see you bench turning it watch oil go thru to pre-lube it also a chance to wreck a good new one there!
To me in person knowns over oil in even 8oz capacity systems 4 oz near certainly that much over still worked just erratic all had top mounted compressor were left alone simply the cost to redo the whole show wasn't justified put up with it the life of that vehicle so can't share in person what I would do or actually did for one like this.
About specs for capacities for this. The printed (from web) chart on this says same capacity as Suburbans and their GMC counterparts for the shorter of all these! CHARTS ALWAYS SAID EVERY PAGE GO BY UNDER-HOOD INFO FIRST not the chart!
With that repeat my chart shows 48oz 134a (dual systems) and 11oz PAG-46 for all Suburbans and these? Just FYI on it if that helps or just adds to troubles? BTW I don't personally think 10% off on real amounts should matter way too much or at all but really will if outside of the 10% area if known,


Tom



Hammer Time
Ultimate Carjunky / Moderator
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Jun 13, 2020, 4:06 AM

Post #9 of 11 (1207 views)
Re: 2001 Chevy Tahoe AC and pressures cannot fix. Sign In

No Tom, it is not the same as Suburbans. The Tahoe is 3 oz. less
Charge with Front and Rear A/C .................... 1.2 kg (2.7 lbs.)


Thingtang

Your pressures are still too high and the main suspect is air flow across the condenser or the condenser itself. Try spraying a mist of water on the condenser while the AC is running to see if the pressures drop dramatically.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Tom Greenleaf
Ultimate Carjunky / Moderator
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Jun 13, 2020, 4:51 AM

Post #10 of 11 (1202 views)
Re: 2001 Chevy Tahoe AC and pressures cannot fix. Sign In

HT - Thingtang? I don't know how to argue with specs, printed, documented and dispersed/published that are WRONG or make room for deviations within models + model years so they ALL should default to OE stickers if they are there or legible.


The end all as HT said should be using water on condenser seeing the results. It will change for sure external evaporating water is 10X or more of just air flow which IMO lacks in most anything plus viscous fan clutches took a dump in quality years ago.
It's only an IMO and once published some designs would suffer heat transfer BACKWARDS or "radiate" again air flow towards condensers I dare say more when vehicle is over a hot surface or limited area for air to flow DOWN and out under it. Drive one around with gauges out of hood to observe could be telling of something bizarre like that?? Tom


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jun 13, 2020, 6:14 AM

Post #11 of 11 (1193 views)
Re: 2001 Chevy Tahoe AC and pressures cannot fix. Sign In

The specs come from Alldata which is created from factory service manuals not something found on the Internet.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.







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