Forums Migration

Please read this thread

Recent Topics
Trust Funds
by stockrex - 07/07/20 07:28 AM
3 on the tree
by Chris142 - 07/07/20 07:21 AM
ROCKAUTO selling old expired stock.
by nicholas - 07/07/20 07:21 AM
Amsoil SS 5w30
by mpgo4th - 07/07/20 06:57 AM
Water/Coolant Contamination?
by nastyc5 - 07/07/20 06:53 AM
07 Tahoe trans fluid change.
by Anthony - 07/07/20 06:06 AM
Ravenol 15W40 Marine
by Realfine69 - 07/07/20 05:10 AM
2020 VW 0W20??
by Realfine69 - 07/07/20 05:06 AM
Who makes the O'reillys trans filters ??
by GMguy84 - 07/07/20 05:00 AM
[Seattle Craigslist] Cheap Pennzoil 5w20
by SlavaB - 07/07/20 02:14 AM
Best Synthetic Oil For Cleaning
by BlueOvalFitter - 07/06/20 11:18 PM
Make your predictions for 20 years from now...
by sloinker - 07/06/20 10:47 PM
Getting rid of carbon in exhaust ports?
by Spetz - 07/06/20 10:15 PM
Rotella Gas Truck 0W-20 VOA
by HDoilDude - 07/06/20 09:57 PM
Two Mobil 1 M1-110A filters. Different sizes
by Dallasmale1970 - 07/06/20 09:46 PM
BITOG forums migrating to Xenforo soon
by wwillson - 07/06/20 09:41 PM
Carburetors - I think I've learned to like them
by Kurtatron - 07/06/20 09:40 PM
Best fuel stabilizer/cleaner ?
by icemanrrc - 07/06/20 09:39 PM
Engine Restorer = Glittery oil?
by nastyc5 - 07/06/20 09:35 PM
Newest Members
sycboi, Chuck_Ellison, BakonBittz, ssoH, Sumpter_al
71869 Registered Users
Who's Online Now
85 registered members (ABN_CBT_ENGR, 86cutlass307, Audioquest, alarmguy, avi1777, Anthony, 10 invisible), 1,323 guests, and 32 spiders.
Key: Admin, Global Mod, Mod
Forum Statistics
Forums67
Topics307,538
Posts5,312,684
Members71,869
Most Online4,538
Jan 20th, 2020
Donate to BITOG
Print Thread
Hop To
Page 1 of 2 1 2
AC Woes #5447631 06/06/20 11:44 AM
Joined: Dec 2005
Posts: 1,280
A
artbuc Offline OP
OP Offline
A
Joined: Dec 2005
Posts: 1,280
Re 1999 Avalon

AC performance is borderline...lots of bubbles in sight glass and 46-48 low temp coming out of center vent. Doors closed, windows down, recirc on, 1800 rpm, 86 degrees and humid. Put on the gages. High side looks ok, around 225. Low side is low, around 25 but bigger problem is low is not stable. It will hold 25 for 15-30 seconds then start pulling down. When fans kick into hi speed, drop accelerates and low side pressure switch kicks off compressor around 15.

I would say I have a restriction in the orifice. Also, when I turn off car, it takes a long time for pressures to equalize. After standing there for several minutes, high side was still 150.

Definitely not going to put serious money into this almost 22 year old car plus at 71, I really don’t feel like doing a major ac overhaul even though I have all the tools and know how.

Could I be missing something easy? Thanks.

Re: AC Woes [Re: artbuc] #5447644 06/06/20 12:03 PM
Joined: Feb 2012
Posts: 169
I
irad Offline
Offline
I
Joined: Feb 2012
Posts: 169
Needs refrigerant. Low should be 35-40 psi with compressor on.

Re: AC Woes [Re: artbuc] #5447648 06/06/20 12:05 PM
Joined: Jun 2013
Posts: 2,149
M
mattwithcats Offline
Offline
M
Joined: Jun 2013
Posts: 2,149
I put a can of PAG oil in...

Seals and compressor get dry...

Note that you can only do this once, or you will drown the system...

You will need a can tap...

https://www.walmart.com/ip/A-C-Pro-...100-with-Ice-32-Oil-Charge-3-oz/16888788


2009 Smart Pure
Pennzoil Platinum Euro 0W-40, Wix XP 51356 filter, 45 mpg...
185/55R15 General HP tires, "H" speed rated, 44 psi (300 kpa)
Re: AC Woes [Re: artbuc] #5447663 06/06/20 12:19 PM
Joined: Feb 2009
Posts: 3,765
J
Jetronic Offline
Offline
J
Joined: Feb 2009
Posts: 3,765
I agree with the blockage, pressures should equalize quickly after shutdown.


AR Giulietta 2.0 JTDM-2 -- Total Quartz 9000 Energy 0w30
Hankook Ventus V12 evo2 235/45R17
Re: AC Woes [Re: artbuc] #5447666 06/06/20 12:26 PM
Joined: Jun 2003
Posts: 21,068
C
Chris142 Online Content
Online Content
C
Joined: Jun 2003
Posts: 21,068
Ignore the bubbles in the sight glass. They do not mean anything with an r134a system. I have learned that diagnosing a r134a system with pressures is nearly impossible. A system can have 1/4 charge but show ok pressures. Have it properly recharged and go from there.


02 Wrangler Napa high milage 10w40
87 F250 Valvoline 15w40
07 fjcruiser Car lube plus 10w30
Z400 castrol T 10w40
Can am Maveric edge 5w40
57 case tractor Chevron sae30
Re: AC Woes [Re: artbuc] #5447668 06/06/20 12:29 PM
Joined: Sep 2015
Posts: 2,725
M
mk378 Offline
Offline
M
Joined: Sep 2015
Posts: 2,725
I'd agree with Chris. The only way to be sure on the charge is have someone with a machine pull it all out and weigh the right amount back in. Anything else is wild guessing.

Overall what you describe though sounds completely normal for a TXV system. I didn't think any Toyotas were CCOT like American cars.

TXV systems don't cycle on pressure. The compressor will cut off when the evaporator temperature becomes low enough to risk freeze-over of the air side. At that point the air from the vents should be about 40 F. The suction line will be similarly cold. Try and get an accurate measurement on the line. The heater could be re-heating air.

If the compressor is cycling on temperature, absolutely nothing you could do to the refrigeration system under the hood will lower vent temperature. The problem would be reheating or lack of air flow due to 20 years of crud in the evaporator.

Last edited by mk378; 06/06/20 12:33 PM.
Re: AC Woes [Re: artbuc] #5447671 06/06/20 12:34 PM
Joined: Jan 2013
Posts: 4,059
W
WyrTwister Offline
Offline
W
Joined: Jan 2013
Posts: 4,059
Originally Posted by artbuc
Re 1999 Avalon

AC performance is borderline...lots of bubbles in sight glass and 46-48 low temp coming out of center vent. Doors closed, windows down, recirc on, 1800 rpm, 86 degrees and humid. Put on the gages. High side looks ok, around 225. Low side is low, around 25 but bigger problem is low is not stable. It will hold 25 for 15-30 seconds then start pulling down. When fans kick into hi speed, drop accelerates and low side pressure switch kicks off compressor around 15.

I would say I have a restriction in the orifice. Also, when I turn off car, it takes a long time for pressures to equalize. After standing there for several minutes, high side was still 150.

Definitely not going to put serious money into this almost 22 year old car plus at 71, I really don’t feel like doing a major ac overhaul even though I have all the tools and know how.

Could I be missing something easy? Thanks.
Most automotive A/C systems have a low pressure switch which turns the compressor clutch coil off , if the low side pressure gets too low . Chances are , the system is low enough on refrigerant that the low pressure switch is causing the compressor clutch to cycle .

I personally try to run the low side pressure around 35 psi , depending on the inside & outside temperatures .


Wyr
God bless
Re: AC Woes [Re: Chris142] #5447695 06/06/20 12:58 PM
Joined: Oct 2014
Posts: 15,531
C
CT8 Offline
Offline
C
Joined: Oct 2014
Posts: 15,531
Originally Posted by Chris142
Ignore the bubbles in the sight glass. They do not mean anything with an r134a system. I have learned that diagnosing a r134a system with pressures is nearly impossible. A system can have 1/4 charge but show ok pressures. Have it properly recharged and go from there.

This.


2015 F150 2.7
2018 F350 6.2
Re: AC Woes [Re: artbuc] #5447698 06/06/20 01:00 PM
Joined: Dec 2005
Posts: 1,280
A
artbuc Offline OP
OP Offline
A
Joined: Dec 2005
Posts: 1,280
Thanks for the responses. I never had a FSM for this car although I did have them for several other Toyota’s with sight glasses. The FSM HDD illustrations showing what the refrigerant should like like when properly vs undercharged. When I replaced the condenser on this car many years ago, I carefully weighed in the charge and added the proper amount of ND-8 oil. The sight glass showed exactly what the FSM said it should.

The key piece of evidence most did not mention was the low side holding steady until the cooling fans kicked into hi speed. Then it rapidly sucked down until the compressor kicked off at around 15 psi. Why would that happen?

Re: AC Woes [Re: Chris142] #5447699 06/06/20 01:02 PM
Joined: Feb 2009
Posts: 3,765
J
Jetronic Offline
Offline
J
Joined: Feb 2009
Posts: 3,765
Originally Posted by Chris142
Ignore the bubbles in the sight glass. They do not mean anything with an r134a system. I have learned that diagnosing a r134a system with pressures is nearly impossible. A system can have 1/4 charge but show ok pressures. Have it properly recharged and go from there.


It only has apparently correct pressures when not in use...


AR Giulietta 2.0 JTDM-2 -- Total Quartz 9000 Energy 0w30
Hankook Ventus V12 evo2 235/45R17
Re: AC Woes [Re: artbuc] #5447709 06/06/20 01:31 PM
Joined: Jan 2013
Posts: 4,059
W
WyrTwister Offline
Offline
W
Joined: Jan 2013
Posts: 4,059
Originally Posted by artbuc
Thanks for the responses. I never had a FSM for this car although I did have them for several other Toyota’s with sight glasses. The FSM HDD illustrations showing what the refrigerant should like like when properly vs undercharged. When I replaced the condenser on this car many years ago, I carefully weighed in the charge and added the proper amount of ND-8 oil. The sight glass showed exactly what the FSM said it should.

The key piece of evidence most did not mention was the low side holding steady until the cooling fans kicked into hi speed. Then it rapidly sucked down until the compressor kicked off at around 15 psi. Why would that happen?


The fan and compressor may energise at the same time , in this case , when the pressure switch turns on .


Wyr
God bless
Re: AC Woes [Re: WyrTwister] #5447719 06/06/20 01:46 PM
Joined: Dec 2005
Posts: 1,280
A
artbuc Offline OP
OP Offline
A
Joined: Dec 2005
Posts: 1,280
Originally Posted by WyrTwister
Originally Posted by artbuc
Thanks for the responses. I never had a FSM for this car although I did have them for several other Toyota’s with sight glasses. The FSM HDD illustrations showing what the refrigerant should like like when properly vs undercharged. When I replaced the condenser on this car many years ago, I carefully weighed in the charge and added the proper amount of ND-8 oil. The sight glass showed exactly what the FSM said it should.

The key piece of evidence most did not mention was the low side holding steady until the cooling fans kicked into hi speed. Then it rapidly sucked down until the compressor kicked off at around 15 psi. Why would that happen?


The fan and compressor may energise at the same time , in this case , when the pressure switch turns on .


That is not what I described. The condenser fans are running and the low side is relatively constant at around 25. When the condenser fans kick into high speed, the low side pressure starts dropping until it kicks the compressor off at 15 psi.

Re: AC Woes [Re: artbuc] #5447756 06/06/20 02:54 PM
Joined: Feb 2009
Posts: 3,765
J
Jetronic Offline
Offline
J
Joined: Feb 2009
Posts: 3,765
All the refrigerant is being moved to the high pressure side which shouldn't happen without blockage. If it was a simple underfill, the low pressure shut off would happen a lot sooner, and you woud not see different pressures on low and high side seconds after shut off.


AR Giulietta 2.0 JTDM-2 -- Total Quartz 9000 Energy 0w30
Hankook Ventus V12 evo2 235/45R17
Re: AC Woes [Re: Jetronic] #5447777 06/06/20 03:38 PM
Joined: Dec 2005
Posts: 1,280
A
artbuc Offline OP
OP Offline
A
Joined: Dec 2005
Posts: 1,280
Originally Posted by Jetronic
All the refrigerant is being moved to the high pressure side which shouldn't happen without blockage. If it was a simple underfill, the low pressure shut off would happen a lot sooner, and you woud not see different pressures on low and high side seconds after shut off.


I agree completely. Just not sure why it only happens when condenser fans kick into high speed.

Last edited by artbuc; 06/06/20 03:39 PM.
Re: AC Woes [Re: artbuc] #5447793 06/06/20 04:11 PM
Joined: Sep 2015
Posts: 2,725
M
mk378 Offline
Offline
M
Joined: Sep 2015
Posts: 2,725
More condenser cooling, high side drops, making it easier for the compressor to pull down the low side.

About half the people here have you convinced there's a switch on the low side doing something. There isn't one. Look at the lines yourself.

Last edited by mk378; 06/06/20 04:12 PM.
Page 1 of 2 1 2
Previous Thread
Index
Next Thread

BOB IS THE OIL GUY® Powered by UBB.threads™