A/C wont build presure or suction

Tiny
XJ6
  • MEMBER
  • 1998 LEXUS LS 400
98 ls 400 AC will not get cold. New compressor, evaporator, expansion valve, recievor dryer and Epr evap presure valve. Car will not build presure or suction. Please Help! SoS! Thank you Mike.
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Tuesday, February 8th, 2011 AT 1:13 AM

18 Replies

Tiny
WRENCHTECH
  • EXPERT
If it doesn't have any compression or suction at all and you're sure you don't have the gauge valves open, you have a bad compressor that could even have a broken shaft.
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Tuesday, February 8th, 2011 AT 1:53 AM
Tiny
XJ6
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Thank you for your quick responce! Yes I have tryed another compressor but I am having the same problem. I check suction and compression at the compressor but once it goes into the car I don't have enough. I replaced expansion valve and epr presure valve for the evap presure. This valve is used with the expansion valve. For some reason on lexus one side is blocked at a evaporator port and it flows around through epr valve. Both parts are new. What else could it be?
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Wednesday, February 9th, 2011 AT 1:35 AM
Tiny
WRENCHTECH
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I don't know what you're doing wrong there but you're definitely doing something wrong. If the compressor is turning, then it is pumping. It doesn't need any other component to have suction and pressure. Are you sure the clutch is actually engaging?
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Wednesday, February 9th, 2011 AT 1:38 AM
Tiny
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Lol! Yes I am sure. I have tryed everything.I tryed to adjust old expansion valve and the old EPR valve to cause some restriction and nothing works.I am going to put the old evaporator back in and adjust the old expasion valve and see if I can get presure of some kind.I need restriction from expansion valve yes? The lexus system is also different then most others.I have been fixing Jaguar Mercedes and BMW for 27 years. Never had this problem! The lexus evaporator has three ports and one of them has no flow on the old one and the new one. One side of the expansion vale is hooked to the port with no flow but the piping sends it back around to the evap presure valve thar also works like the expansion valve. I don't know what is wrong!
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Wednesday, February 9th, 2011 AT 2:56 AM
Tiny
WRENCHTECH
  • EXPERT
I don't know what to tell you. As soon as the compressor rotates, it starts pulling from one and and pushing from the other. Just having an expansion valve in place will give you some resistance, even if it's stuck wide open. You can't have static pressures unless the compressor is totally wiped out or not even engaged.
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Wednesday, February 9th, 2011 AT 3:04 AM
Tiny
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I checked the compressor from the high side hose and also from the suction hose. I have both presure and suction but when I connect the hoses to the system and put my gauges on with the correct amount of r134 my gauges stay at 150 high side and 25 suction with no change even when I excellerate the engine. It does the same thing as the original compressor was doing. The car came in with a leak and I replaced evaporator. When I charged up the system this is what has been happening.I replaced everything but the condensor and I check the condesor and there is no blockage. How much presure do I need from compressor? I hooked a compression gage to it and it blows my hand off of it at 95 psi.
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Wednesday, February 9th, 2011 AT 4:12 AM
Tiny
WRENCHTECH
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Now you've got me totally confused. That statement is entirely different from what you have been saying. You now say you have 150 high side and 25 low side. That's not so far off and quite different from no pressure at all.
I don't know how you determined there was no blockage in the condenser because that can't be done since it's a "bypass" type and will show flow even if 90% blocked but I doubt that has any issues here. Other than the high side being a little low, I don't see the big issue. I don't know what kind of outside temp you're working in but that could have a lot to do with your problems. You may not have enough refrigerant in it either.
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Wednesday, February 9th, 2011 AT 1:07 PM
Tiny
XJ6
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I tryed to add more freeon and my outside temp is between 65 and 75 degrees. The inside temp blows about the same temp. My gauges do not move and I see only slight bubbles moving in the system through site glass on dryer. The dryer is new too. The low side pipe does not get cold and the high side does not get hot. It seems to have constant flow like a cooling system. No restriction in the expansion valves turning freeon back to liquid. That's how it seems to me. I tryed everything. Thank you for keeping up with my email. What else can you tell me?
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Wednesday, February 9th, 2011 AT 1:42 PM
Tiny
WRENCHTECH
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Feel the temp of the liquid line between the condenser and the evap. Is it room temp, warm to the touch or too hot to hold?
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Wednesday, February 9th, 2011 AT 1:46 PM
Tiny
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The liquid line stays room temp all the time. No change anywhere on the system and the suction lines do not get cold at all either when compressor is running. They stay room temp.
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Wednesday, February 9th, 2011 AT 2:23 PM
Tiny
WRENCHTECH
  • EXPERT
OK, that is indicating a total blockage in the system. That line should be warm to the touch, not hot, to indicate flow. I think your dryer would be highly suspect here.
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Wednesday, February 9th, 2011 AT 2:26 PM
Tiny
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It is room temp.
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Wednesday, February 9th, 2011 AT 3:16 PM
Tiny
WRENCHTECH
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I know. You said that.
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Wednesday, February 9th, 2011 AT 3:18 PM
Tiny
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I have the car here again today and I was about to take expansion valve out and adjust the flow but like I explained they are only using one side of it going to the third port on the evaporator and then the piping is rerouted to the evap presure valve. Why do they have three ports on evaporator?That is also new from Lexus. Did you have a new idea of why the flow and temp of the pipes are room temp?
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Wednesday, February 9th, 2011 AT 7:11 PM
Tiny
WRENCHTECH
  • EXPERT
You know, you're not listening to anything I'm saying so I'm going to back out of this. All you're going to accomplish now is to ruin a good expansion valve. I told you I suspected the dryer to be restricted but you have your own ideas. Good luck.
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Wednesday, February 9th, 2011 AT 7:21 PM
Tiny
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Ok thanks for your help! I mentioned that I already replaced the dryer. I was going to adjust the old expansion valve and try that. I have a lot of hours into this and two friends and myself with over 25 years experiance and we can't figure it out yet. I will let you know what it was when I fix it. Thanks again! Mike
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Wednesday, February 9th, 2011 AT 7:37 PM
Tiny
WRENCHTECH
  • EXPERT
You might want to do a little research on A/C theory before you tackle something like this again because I believe you are way off the mark. I live in South Florida and have done extensive A/C work for many years. You have all the symptoms of a blockage at the dryer and you could analyze this further by feeling the temp of that line from the time the system is started. If it never gets warm, it means you have to travel to that point. You will also notice very little flow (movement) in the sight glass.
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Wednesday, February 9th, 2011 AT 7:49 PM
Tiny
XJ6
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I want to thank you for your input! I put in another evaporator after I took out the the new one I already replaced. The third port on a lexus evap was clogged from the factory when they made the new part. I am sorry if my explanation of problems were not clear. You had good input and I would like to keep in touch. I have a lot of info I could share as well so keep me posted Via email. Mike. Jag benz and BMW of Melbourne fl. 32958 jagnbenz1@juno. Com
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Thursday, February 10th, 2011 AT 3:51 AM

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