lets talk a/c
Thread Starter
TECH Enthusiast
Joined: Jul 2003
Posts: 734
Likes: 7
From: Imperial Valley, CA
lets talk a/c my ac has not been cooling as much and i had it checked out. it seems like it has plenty of gas, so i know thats not the problem. what else can it be besides the compressor?
Im sure the mods will move this... check your condensor in the front of the car could be clogged with road grime, blow it out with an air nozzle or a water hose. That being clogged can cause poor A/C performance.
There is a door in the HVAC unit that open/closes when you switch to using heat. There is also a low pressure switch in the A/C line that controls the A/C compressor. Do a couple simple things first, with the car idling see if the A/C compressor is running all the time, you can look at the clutch to make sure its engaged. Second find the larger line that goes into the HVAC unit at the firewall and feel it, should be pretty ice cold, the smaller line should be pretty warm/hot.
Could be a lot of things. I am an a/c tech. 
The refrigerant never goes bad and never needs to be topped off unless theres a leak.
The pressure switch could be going bad.
There is an orifice that could get clogged, but it's a closed system- if it's clogged it's clogged with (usually) worn compressor parts.
If the compressor is going out it will usually become more noisey.
Could be a fan relay, the low speed engine cooling fan should come on with the compressor.
If the system has ever been worked on or added freon to, it could be contaminated, usually with air. It might cool well still but you will notice it on real hot days.
Could be a dirty blower (inside the car), a piece of paper or something sucked into the air intake, or the evaporator coil may be dirty and restricting airflow.
You should get a 40 to 50 degree temperature difference between outdoor air temp and temp of air coming out of the vent.
What are your pressures and temperatures?
You can pinch the heater hoses off to be sure no coolant goes to the heater core just to test that the heat door isn't open.
The refrigerant never goes bad and never needs to be topped off unless theres a leak.
The pressure switch could be going bad.
There is an orifice that could get clogged, but it's a closed system- if it's clogged it's clogged with (usually) worn compressor parts.
If the compressor is going out it will usually become more noisey.
Could be a fan relay, the low speed engine cooling fan should come on with the compressor.
If the system has ever been worked on or added freon to, it could be contaminated, usually with air. It might cool well still but you will notice it on real hot days.
Could be a dirty blower (inside the car), a piece of paper or something sucked into the air intake, or the evaporator coil may be dirty and restricting airflow.
You should get a 40 to 50 degree temperature difference between outdoor air temp and temp of air coming out of the vent.
What are your pressures and temperatures?
You can pinch the heater hoses off to be sure no coolant goes to the heater core just to test that the heat door isn't open.
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^^^^yup. i had one come in for not blowing as cold as it should and i ended up replacing the orifice tube and a compressor. not sayin its the compressor for sure but that orifice tube might need replacing.
On The Tree
Joined: Apr 2007
Posts: 157
Likes: 0
From: Way Out In The Boonies Chasin' Hill Billies, North GA
Even on a 100 deg day I don't like to see air out of the vents hotter than approx 50 - 55 deg. Go get a thermometer (like you would stick in a turkey) and put it in the vent w/ the blower motor on 2, max air, and recirc. Tell us the temp coming out of the vents and we MAY be able to help....lots of factors come into play w/ A/C.....not having the proper equipment to diagnose a problem is like trying to find a needle in a haystack. You may as well be guessing.
topdown, i agree with you. but, to add to that if the vent temp is 50-55 the ambient temp in the car will not be anywhere near that. i hear this complaint on a DAILY basis at work...
Staging Lane
Joined: Nov 2003
Posts: 76
Likes: 0
have you checked it with a set of reliable manifold gauges? The Delphi Compressor, not sure which model, probably a V-7 has teflon rings on each piston and if one or a partial ring comes loose then it will just go down the line and eventually clog up the orifice tube, which acts like the filter for the A/C system. I would definitely pull the orifice tube and see if its clean. You will then need to pull a vacuum on the system to ensure there is no moisture in the system and induce 2 cans of refrigerant and I would also buy a 4 oz can of oil charge..
B.
B.
Originally Posted by SLawson86
has anyone considered that it has been hotter outside? i stick with the rule that the ac will only cool 16-20 degrees cooler than the outside air temp...
If what you're saying was correct 100 outdoor temp and a 20 difference would mean 80 degrees coming out of the vent. To me thats a system thats not working.
I am an a/c tech I drive around with a spare thermometer in the work vans vent and it gets to 50-55 no problem on a 95 degree day.
Automotive a/c is refered to as direct cooling, meaning it blows directly on the occupants therefore ambient (surrounding air) inside the car doesn't matter much it will cool eventually but the air blowing right on you is what provides comfort. Totally opposite of a house a/c system, in fact 16-20 degree split between intake air and discharge air temp is what we shoot for, almost sounds like you're talking about house a/c.
Originally Posted by Bryan28
have you checked it with a set of reliable manifold gauges? The Delphi Compressor, not sure which model, probably a V-7 has teflon rings on each piston and if one or a partial ring comes loose then it will just go down the line and eventually clog up the orifice tube, which acts like the filter for the A/C system. I would definitely pull the orifice tube and see if its clean. You will then need to pull a vacuum on the system to ensure there is no moisture in the system and induce 2 cans of refrigerant and I would also buy a 4 oz can of oil charge..
B.
B.
