Automotive AC help
Ok...its a 2009 ford expedition with high mileage.
The other day the AC just randomly stopped working. It was blowing fine the day before.
I checked all associated fuses and relays. They all tested good.
The compressor will simply not cycle on. I know that could be the cause of a bad compressor a bad electrical connection or a pressure switch protecting the compressor.
I put a manifold gauge set on the system. Both while the engine was off, and while the engine was running the pressures on both the high and low side read approximately 65psi. Temperature was 85F-90F.
Just for grins and giggles, I put a vacuum on the system for a good 45 minutes. Shut it off and it held -29.9 inches fine...25 min or so later I decided to charge the system with the hope that the switches would now allow the compressor to cycle on.
As the pressure rose on the low slide the high side pressure slowly raised as well but with a slight lag and never really caught up. The pressure stabilized at 65 psi on both sides, the compressor never kicked on. Yes, I made sure I was only charging via the low side and the AC was on full blast with doors open....temp of the air never dropped as the compressor never kicked on.
What do you think?
The other day the AC just randomly stopped working. It was blowing fine the day before.
I checked all associated fuses and relays. They all tested good.
The compressor will simply not cycle on. I know that could be the cause of a bad compressor a bad electrical connection or a pressure switch protecting the compressor.
I put a manifold gauge set on the system. Both while the engine was off, and while the engine was running the pressures on both the high and low side read approximately 65psi. Temperature was 85F-90F.
Just for grins and giggles, I put a vacuum on the system for a good 45 minutes. Shut it off and it held -29.9 inches fine...25 min or so later I decided to charge the system with the hope that the switches would now allow the compressor to cycle on.
As the pressure rose on the low slide the high side pressure slowly raised as well but with a slight lag and never really caught up. The pressure stabilized at 65 psi on both sides, the compressor never kicked on. Yes, I made sure I was only charging via the low side and the AC was on full blast with doors open....temp of the air never dropped as the compressor never kicked on.
What do you think?
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check the low pressure switch I have had to change out several over time on different vehicles
a fast way to test IT just use a jumper wire ( paper clip will work ) to by pass the switch see it the compressor starts up0 -
You're beyond me with this talk of pressures but can you disconnect the wire to the compressor and check for voltage there? Don't give up on the compressor, it could be the clutch. If you're going to draw the system down, consider changing the condenser. It's right up front and takes a beating and they're cheap. Recently I replaced the compressor, condenser, and expansion valve in my 07 CRV. The expansion valve was a trip to hell to change. It's at the top of the firewall up under the dash. I'm not sure exactly what it does but I read where it should be changed and it was $12 or so. 0 -
check voltage at clutch, none check inside controls, turn temp control all way to cold, push max button, push ac button, jumper low and high pressure switches under hood still no voltage possibly break in wire. 0 -
check voltage at clutch, none check inside controls, turn temp control all way to cold, push max button, push ac button, jumper low and high pressure switches under hood still no voltage possibly break in wire. 0 -
I worked on my daughter in laws Honda.It was doing the same thing yours is doing.Put the gauges on it,everything looked good,but the compreeor would not cycle on.Call someone smarter than me and it was the relay. 0 -
Since this is one area I never really worked on just took it to a shop. I will just ask one question.
The reason for this on is my car has scared me a couple of times acting like the AC would not work. In my Car you have to push a button to turn the ac on and set temp to cold. But what gets me and its cause I never shut it off . The fan speed has an Off position. Some how it will get turned off. Make sure yours is on.
Any more help after that and I take it to a shop. Only drive my truck in the winter or Not super hot days. AC is out.0 -
I do a lot of work on Automotive ACs... If it's not a fuse or relay, the first thing I would check to see if there's enough freon in it. Because that's usually what it is. They will work just fine until they get to ascertain pressure and then completely stop.
If there's enough freon in it, then I would look to make sure you're getting power to your air compressor.
The last place I would look is the expansion valve. But they're cheap enough to buy, usually less than $20. But are usually inside your dash by your evaporator. So they're not that easy to replace...0 -
65 PSI is undercharged, get your pressures up to at least 95 to kick in the clutch. and go from there. 0 -
quote:Originally posted by Ditch-Runner
check the low pressure switch I have had to change out several over time on different vehicles
a fast way to test IT just use a jumper wire ( paper clip will work ) to by pass the switch see it the compressor starts up
This will engage compressor and get charge into system. Sounds like ground wire break. The clutches do go out but not very frequently.0 -
[:I] its been beat to death but go to you tube with your specific car and issue I will bet there is a least a few post on checking and repairing it
I ahve tinkered and worked on cars for almost 50 years .. I can add I wish youtube had been around when i was a teenager . even if I know I find my self going to the site just to see other ways
just recent I found one on my old 8n ford tractor some classic tractor place telling people to use a specific old plug not the new replacement versions cross referenced plug .. I did so it starts better then it has for many years0 -
quote:Originally posted by Ditch-Runner
[:I] its been beat to death but go to you tube with your specific car and issue I will bet there is a least a few post on checking and repairing it
I ahve tinkered and worked on cars for almost 50 years .. I can add I wish youtube had been around when i was a teenager . even if I know I find my self going to the site just to see other ways
just recent I found one on my old 8n ford tractor some classic tractor place telling people to use a specific old plug not the new replacement versions cross referenced plug .. I did so it starts better then it has for many years
Do this and it would even start better.[:D]
https://www.youtube.com/watch?v=DxlYVCXPFhw0 -
The compressor has to run in order to check for correct pressure readings. (and you will have to jumper the low pressure safety switch or jump 12v direct to the clutch to get a compressor run so as to fill with Freon)
Most generally takes about 3 lbs of Freon to start getting correct pressure reading.0 -
Finally found the pressure cut off switch. It's got correct voltages across its connector that connects to the switch. I plugged it back in then put my voltage meter across the connector that connects to compressor itself. When I had the wife push the AC button to the on position I showed 14 volts across it.
I'm pretty much thinking it's the clutch at this point. Given it's an 09 with 267k miles...I'll likely replace it along with the compressor, and dryer/desiccant.0 -
trust me I have thought about it [}:)][}:)][}:)][:p]
quote:Originally posted by grumpygy
quote:Originally posted by Ditch-Runner
[:I] its been beat to death but go to you tube with your specific car and issue I will bet there is a least a few post on checking and repairing it
I ahve tinkered and worked on cars for almost 50 years .. I can add I wish youtube had been around when i was a teenager . even if I know I find my self going to the site just to see other ways
just recent I found one on my old 8n ford tractor some classic tractor place telling people to use a specific old plug not the new replacement versions cross referenced plug .. I did so it starts better then it has for many years
Do this and it would even start better.[:D]https://www.youtube.com/watch?v=DxlYVCXPFhw0 -
quote:Originally posted by Okie743
The compressor has to run in order to check for correct pressure readings. (and you will have to jumper the low pressure safety switch or jump 12v direct to the clutch to get a compressor run so as to fill with Freon)
Most generally takes about 3 lbs of Freon to start getting correct pressure reading.
Not exactly sure what you mean. If I had vacuumed the system down completely to a neg 29.9inches and started introducing refrigerant to the low side it should kick on relatively fast.
Also my entire system capacity is less than 3 pounds of refrigerant.0 -
Not sure about Fords, nor all these newfangled computers they call cars, but nobody mentioned the Full-Trottle cut out switch. Drops the Compressor when asking for full throttle. Rug and old age shut me off that way once...found it after a lot of useless work! Could of course be in the wiring between the switch and Compressor. 0 -
Yep, do the drier too. And also, you have to measure the amount of oil that comes of your old compressor then add that much to the new one, unless it already comes with oil. The amount that's in the new one, in that case should be on a lable somewhere on the new comp. The type of oil is specific to your vehicle. 0 -
if your going to replace most of the system as you state
you might go ahead and replace the condenser and filter they plug up easy the lines are so small and not that expensive to do while you you have it down I just went that route on my 97 chevy
and I have all the parts set aside to do my older 94 in the next couple weeks0 -
I am actually replacing the front AC blower motor in my Expedition tonight.
$100 part and easy swap. If I read your post correctly you said it was BLOWING fine the day before. I take this to mean you are not getting air circulation, not that you are circulating warm air.
Is the rear AC in your Expedition blowing cold air?
Maybe this helps:
https://m.youtube.com/watch?v=PlN8lNu9NzQ0 -
The blowers are working fine. It's that the air is not being cooled. The compressor is not kicking on which is why I have been isolating the electrical side of the system and the vaccum/refrigerant side of the system to trouble shoot. It seems that the electrical system, at this point is telling the compressor/clutch to engage when I request AC from the PCM. So I am assuming (dangerous I know) that the electrical system up to the compressor is working properly.
I am further inclined to believe this as after I vacuumed the system, and it held the vaccum that after I induced refrigerant it did not want to cycle. I am not sure what else it could be at this point...0 -
My Buick was freon low and wouldnt cycle until disconnecting bsttery. Had great air 5 seconds later 0 -
quote:Originally posted by kidthatsirish
The blowers are working fine. It's that the air is not being cooled. The compressor is not kicking on which is why I have been isolating the electrical side of the system and the vaccum/refrigerant side of the system to trouble shoot. It seems that the electrical system, at this point is telling the compressor/clutch to engage when I request AC from the PCM. So I am assuming (dangerous I know) that the electrical system up to the compressor is working properly.
I am further inclined to believe this as after I vacuumed the system, and it held the vaccum that after I induced refrigerant it did not want to cycle. I am not sure what else it could be at this point...
Put a new compressor in it.0 -
Did you say you have 12v at the compressor clutch? (checking the voltage right at the compressor clutch wire?)
AND is the compressor running?0 -
quote:Originally posted by kidthatsirish
The blowers are working fine. It's that the air is not being cooled. The compressor is not kicking on which is why I have been isolating the electrical side of the system and the vaccum/refrigerant side of the system to trouble shoot. It seems that the electrical system, at this point is telling the compressor/clutch to engage when I request AC from the PCM. So I am assuming (dangerous I know) that the electrical system up to the compressor is working properly.
I am further inclined to believe this as after I vacuumed the system, and it held the vaccum that after I induced refrigerant it did not want to cycle. I am not sure what else it could be at this point...
12 volt at clutch and no go means clutch is shot.0 -
Take a vom or DMM and check the resistance of the clutch coil.
A complete aftermarket clutch assembly is available for most compressors, which is the coil, clutch and bearing as a assembly or each one is available as a separate item.
If it has 12v at the clutch wire and the compressor is not operating the clutch or compressor is bad.
You can review the clutch repair procedure for your make of compressor and special tools needed on you tube.
Might be easier to just replace the compressor.
Check prices online at rockauto.com. Some require a core trade in, some don't. Hang onto your receipts because it's required for a warranty replacement and it is quite common for aftermarket compressors to need a warranty exchange.0 -
Yeah I went ahead and ordered a new compressor (why replace a clutch on a compressor with that many miles when I will have to take the compressor out anyway?) as well as a new dryer and new front and rear valves. We will see how it all works out when I get everything off of it. 0
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