AC won't blow cold.
04-27-2016, 10:59 PM
#1
Thread Starter
AC won't blow cold.
For the past year or so I've been sorting out issues with a car that I bought that has a rebuilt title (prior salvage). After dealing with more major issues I'm finally able to tackle some low hanging fruit.
Anyway the AC in the car never worked and the AC compressor was making a ton of noise. I replaced the AC compressor and it no longer makes noise. I then proceeded to get freon filled at my local shop and the system had no leaks. Unfortunately, the car still doesn't blow cold air. The mechanic at the shop informed me that the car may have a bad expansion valve. After doing some research online this looks like it could be a possibility. I'm wondering if any of you have any other suggestions as to what the problem may be or how I can diagnose it. I am admittedly not familiar with AC.
Anyway the AC in the car never worked and the AC compressor was making a ton of noise. I replaced the AC compressor and it no longer makes noise. I then proceeded to get freon filled at my local shop and the system had no leaks. Unfortunately, the car still doesn't blow cold air. The mechanic at the shop informed me that the car may have a bad expansion valve. After doing some research online this looks like it could be a possibility. I'm wondering if any of you have any other suggestions as to what the problem may be or how I can diagnose it. I am admittedly not familiar with AC.
04-28-2016, 03:57 AM
#2
It's usually the drier that gets clogged on this car, this raises pressure in the high pressure line and will cause it to leak. Since its a small pressure leak it'll pass the vacuum test. Another thing that can happen is the dryer stops drying and the expansion valve freezes over because of the moisture in the charge. But when that happens it usually triggers the thermal protection on the compressor. Since your compressor works but it's not blowing cold I'm guessing you should replace the drier and expansion valve, and fix any leaking hose you have. Hopefully it's not the compressor shaft seal.
Try this, run your fingers up and down the high pressure hose, if you notice any oily residue, that's your problem right there. Replacing that hose can be tricky, particularly when you try to remove the bolt from the condenser. What happens is that the moisture mixes with the oil and refrigerant it corrodes the bolt and it softly brakes off.
The only way to fix this is to drill through the condenser and part of the bolt. Only the threads on the upper left corner are actually sealing the condenser so if you drill straight through the bolt ull cause another leak or crack the mounting block on the condenser.
Try this, run your fingers up and down the high pressure hose, if you notice any oily residue, that's your problem right there. Replacing that hose can be tricky, particularly when you try to remove the bolt from the condenser. What happens is that the moisture mixes with the oil and refrigerant it corrodes the bolt and it softly brakes off.
The only way to fix this is to drill through the condenser and part of the bolt. Only the threads on the upper left corner are actually sealing the condenser so if you drill straight through the bolt ull cause another leak or crack the mounting block on the condenser.
04-28-2016, 02:10 PM
#3
Oh when you recharge the system you have to make sure whoever does it adds the right amount of oil, and it's better to slightly undercharge the system.
04-28-2016, 04:39 PM
#4
Thread Starter
I don't think there is oily residue on the lines? If so it must be really dried out. I took some pictures for ya.
I guess I should note that this car sat in a scrap yard for about 9 years before being rebuilt.
04-28-2016, 09:52 PM
#6
Thread Starter
04-29-2016, 07:07 AM
#7
The oil viscocity for our system is PAG 47 oil, it's not absolutely critical but it will affect longevity. Total system capacity is 4oz(and it's important that you don't overfill either), also if the compressor is making horrible noises I hope it's not grinding itself to oblivion depositing metal shards everywhere. DO NOT RUN THAT COMPRESSOR until you fix it because if the evaporator in the cabin gets filled with metal shavings you'll be in for a world of hurt. The line to check is the thin one coming from the compressor to the condenser, that's the one that usually goes bad. If all your lines are in tip top shape then maybe just add some oil and take some refrigerant out. The compressor won't work if pressure goes over a set limit.
In fact without a decent manifold gauge, a vacuum pump, a service line, an oil injector, and a tank I wouldn't even bother servicing the A/C system. You can't just charge the system and be done with it, when the system starts leaking it leaks more than just refrigerant, this is because the oil mixes so well with it that it too will leave. So ok great your top off your refrigerant but you didn't replace the oil you lost and great it works for a while until it doesn't.
The most damaging thing to the A/C system isn't leaks per se, it isn't even a lack of oil, you just add until it stops making noise. No the most damaging thing is moisture, it's a losing battle because the oil absorbs it, and the only thing you have to control moisture is the drier, and let's be honest, that part is the better part of a decade old on most of these cars. I say every 7 years, you should vacuum the entire system for an hour and replace the drier, the expansion valve is a quality unit and doesn't need to be replaced ever unless it's frozen over.
Vacuuming the system is very important because the low pressure will boil any or moisture that's left in the system, and make it much easier to remove since gas follows vaccums better than droplets of water. Once you've done a good vacuuming with the car off, then you charge the system, with the car on.
https://www.youtube.com/watch?v=lglPJuBXVeE
not horrible description of how to properly charge a system.
In fact without a decent manifold gauge, a vacuum pump, a service line, an oil injector, and a tank I wouldn't even bother servicing the A/C system. You can't just charge the system and be done with it, when the system starts leaking it leaks more than just refrigerant, this is because the oil mixes so well with it that it too will leave. So ok great your top off your refrigerant but you didn't replace the oil you lost and great it works for a while until it doesn't.
The most damaging thing to the A/C system isn't leaks per se, it isn't even a lack of oil, you just add until it stops making noise. No the most damaging thing is moisture, it's a losing battle because the oil absorbs it, and the only thing you have to control moisture is the drier, and let's be honest, that part is the better part of a decade old on most of these cars. I say every 7 years, you should vacuum the entire system for an hour and replace the drier, the expansion valve is a quality unit and doesn't need to be replaced ever unless it's frozen over.
Vacuuming the system is very important because the low pressure will boil any or moisture that's left in the system, and make it much easier to remove since gas follows vaccums better than droplets of water. Once you've done a good vacuuming with the car off, then you charge the system, with the car on.
https://www.youtube.com/watch?v=lglPJuBXVeE
not horrible description of how to properly charge a system.
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04-29-2016, 04:39 PM
#8
Thread Starter
The oil viscocity for our system is PAG 47 oil, it's not absolutely critical but it will affect longevity. Total system capacity is 4oz(and it's important that you don't overfill either), also if the compressor is making horrible noises I hope it's not grinding itself to oblivion depositing metal shards everywhere. DO NOT RUN THAT COMPRESSOR until you fix it because if the evaporator in the cabin gets filled with metal shavings you'll be in for a world of hurt. The line to check is the thin one coming from the compressor to the condenser, that's the one that usually goes bad. If all your lines are in tip top shape then maybe just add some oil and take some refrigerant out. The compressor won't work if pressure goes over a set limit.
In fact without a decent manifold gauge, a vacuum pump, a service line, an oil injector, and a tank I wouldn't even bother servicing the A/C system. You can't just charge the system and be done with it, when the system starts leaking it leaks more than just refrigerant, this is because the oil mixes so well with it that it too will leave. So ok great your top off your refrigerant but you didn't replace the oil you lost and great it works for a while until it doesn't.
The most damaging thing to the A/C system isn't leaks per se, it isn't even a lack of oil, you just add until it stops making noise. No the most damaging thing is moisture, it's a losing battle because the oil absorbs it, and the only thing you have to control moisture is the drier, and let's be honest, that part is the better part of a decade old on most of these cars. I say every 7 years, you should vacuum the entire system for an hour and replace the drier, the expansion valve is a quality unit and doesn't need to be replaced ever unless it's frozen over.
Vacuuming the system is very important because the low pressure will boil any or moisture that's left in the system, and make it much easier to remove since gas follows vaccums better than droplets of water. Once you've done a good vacuuming with the car off, then you charge the system, with the car on.
https://www.youtube.com/watch?v=lglPJuBXVeE
not horrible description of how to properly charge a system.
In fact without a decent manifold gauge, a vacuum pump, a service line, an oil injector, and a tank I wouldn't even bother servicing the A/C system. You can't just charge the system and be done with it, when the system starts leaking it leaks more than just refrigerant, this is because the oil mixes so well with it that it too will leave. So ok great your top off your refrigerant but you didn't replace the oil you lost and great it works for a while until it doesn't.
The most damaging thing to the A/C system isn't leaks per se, it isn't even a lack of oil, you just add until it stops making noise. No the most damaging thing is moisture, it's a losing battle because the oil absorbs it, and the only thing you have to control moisture is the drier, and let's be honest, that part is the better part of a decade old on most of these cars. I say every 7 years, you should vacuum the entire system for an hour and replace the drier, the expansion valve is a quality unit and doesn't need to be replaced ever unless it's frozen over.
Vacuuming the system is very important because the low pressure will boil any or moisture that's left in the system, and make it much easier to remove since gas follows vaccums better than droplets of water. Once you've done a good vacuuming with the car off, then you charge the system, with the car on.
https://www.youtube.com/watch?v=lglPJuBXVeE
not horrible description of how to properly charge a system.
05-02-2016, 06:23 PM
#9
Thread Starter
Just pulled the line to the condenser out and found no metal shavings so I'm guessing the system is OK. I'm going to buy a working AC compressor, install the drier I ordered and then get the system refilled with oil this time.
05-16-2016, 06:01 PM
#10
Thread Starter
New drier is in. Here is the condition of the oil expansion valve. All the o rings look good.
If anyone is wondering, yes you can remove the expansion valve from the front of the firewall. Time to put it all back together. Will get the AC recharged with oil this time and pray for the best.
If anyone is wondering, yes you can remove the expansion valve from the front of the firewall. Time to put it all back together. Will get the AC recharged with oil this time and pray for the best.