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How to remove 2005 Honda Odyssey AC compressor:

I couldn't fit my compressor through the wheel well; instead, I disconnected the radiator hoses (just the two large hoses) and moved the radiator out of the way. I kept the oil lines attached, so all I did was move it out of the way; I didn't remove it from the car. Actually, my wife held it up while I unbolted the compressor. And since I had already remove the condenser, removing the radiator seemed like the logical next step.

I did have to drain the coolant (and will have to replace it afterwards), but the compressor was SO EASY to get to after that. I had almost a clear shot to ever bolt, and detaching the AC hoses and removing the compressor from the car was easy.
 

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For the hoses, I've been looking into a solvent flush. However, I think the system would cost more than simply buying new hoses.

 

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$17 at AutoZone, this is the best solution for cleaning hoses (instead of replacing them). But this is just for the hoses, not the complete system.

Now, keep in mind that I've already removed the compressor and condenser and the hoses that attach to those --

Here is my plan:
- Clean the hoses that I've detached with this fancy can of spray
- Follow that with compressed air to make sure hoses are clear
- Install my new compressor
- Install my new condenser (and dryer)
- Attach cleaned hoses to new components (new o-rings w/ a dab of PAG oil), but leave them detached to the rest of the system
- Take care down to a shop that will properly flush the rest of the system, attach my hoses, and install refrigerant.

 

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The only things I would point out are that the receiver/dryer absorbs moisture so you don't want to leave the system open with the new dryer installed.

If you already have everything removed from the vehicle and are replacing the condenser,dryer, and the compressor, and then flushing the hoses, that only leaves the evaporator and expansion valve to be flushed and cleaned. Would it not be easier to flush and clean that before putting it back together? Then once the evaporator is clean, put it all back together, vacuum it down and then add a fresh charge. Make sure you properly charge the system with oil. You basically have a dry system with exception of whatever comes in the compressor.
 

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The only things I would point out are that the receiver/dryer absorbs moisture so you don't want to leave the system open with the new dryer installed.

If you already have everything removed from the vehicle and are replacing the condenser,dryer, and the compressor, and then flushing the hoses, that only leaves the evaporator and expansion valve to be flushed and cleaned. Would it not be easier to flush and clean that before putting it back together? Then once the evaporator is clean, put it all back together, vacuum it down and then add a fresh charge. Make sure you properly charge the system with oil. You basically have a dry system with exception of whatever comes in the compressor.
Excellent point. I mean, why not? I figured it would be too difficult to flush the entire system; however, now that I look at it, I see that it's doable. Thanks for the encouragement. :)

I've since found this video that demonstrates it all --

 

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I just drained and filled the oil in a 2002 Mustang GT AC compressor and it seemed to go in one port better than the other. Just pour it into whichever one will accept the amount you need to put in. I put some in each port.
 

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Old thread resurrection. This DIY worked great on an 07 Pilot for me last week. Fubar'd clutch and stator, apparently due to leaking PAG oil from the shaft seal. I have a gage set anyways, so I only paid a shop for the evacuation. Old system still held 10 oz that they were able to recover.
One trick I used not discussed here was that instead of paying a shop to recharge, I used my manual MightyVac to pull decent vacuum after assembly (-25). I then left the system under vacuum all night both to check for leaks and make sure ANY condensed water that might have gotten into the system would be vaporized. Next evening I verified it was still under vacuum, pulled it down as far as my hand pump could take it, then hooked up to charge.
First you pierce the can to pressurize the gage set with all the connectors attached and valves closed.
Next, vent a little of the gage system on the can side to purge the 134a / air mixture and make it 100% 134a in there.
Before you open the valve to the low pressure side of the car system, use a precise kitchen scale to weigh the 134a can AFTER the air purge. This is your net start weight.
Now start the car and turn the AC on max. Compressor won't trigger right away if the line pressure sensor is working right.
Open the low pressure side valve on the gage manifold set and let the can empty into the system. If it's a cool day, a hair dryer will help the 134a in the can vaporize.
Once the can is empty (a good shake will tell you), record the empty weight and subtract it from your net start weight. The difference is how much you put in.
Repeat with following cans as necessary until you achieve the specified system 134a weight. (26.5 oz in the Pilot).
Pep Boys only charged me $33 to evac the system, but would have charge me another $60 to refill. [email protected] cans at Walmart were $16.
 

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Wow. I would NOT recommend you do it this way (the hand vacuum pump.) The thing to remember is that the vacuum does more than just allow you to put the refrigerant in. Pulling the vacuum down to 29" boils off any moisture in the system. If you don't pull it down that far you can be left with moisture in the system that will lead to premature failure. Since your system was open for a while during repair you have moisture in there from the air.

Everything else is good info. One tip, and it's what I do, is to get two refrigerant can taps. No matter how you do it (using the 12oz cans from Walmart) you will be left with a partial can. So, since the first can is the easiest to get into the system simply put a partial can in first. So, for example, if you need 26.5 oz in the system, just put in 2.5 oz from the first can. Then close it up and put on a new can with your other can tap. Then add the full second and third cans until they're empty. No more measuring required. Be sure to purge each time.

The last system I did was on a cool day. I was able to get the full charge into the system by using a bucket of hot water to put the can in. I didn't even have to start the engine and run the compressor. Since the system was cool and the refrigerant was warm it all went in.

Again, though, that initial vacuum down to 29" is really important. Running it that way for 30 mins or so boils all the moisture out of the system. Letting it sit for another 30 mins tells you whether the system has any leaks.
 

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Yes, as John said 25 is not a good vacuum. At 25 inHg, the boiling temp of water is still over 130 deg F, meaning that you aren't evaporating the water. At 29 it is near room temp, and 29.9 inHg it is sub zero, so you can get more evap at that level.
 

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The hand pump pulls the vacuum down to that point but doesn't continue venting the moisture that was in there so the moisture evaporated but stayed in the system. There's a high chance you'll have moisture-caused premature failure. If it was only $60 to have it filled I'd sure pay that. Around here it's $150 for a service.

All that said, you can rent (for free) an AC system vacuum pump from Autozone. I did it a few times before I finally bought my own from Harbor Freight.
 

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Ah, Mr. Clark. We meet again. I'm still waiting for my "must replace" bolts in my timing belt job to bust too since I scorned replacing them. I appreciate meticulous, but I maintain that some folks overdo it.

It's true that water doesn't boil at -25. But I didn't submerge the stupid truck for crying out loud. The system was exposed to atmosphere for all of 2 hours during the job (the failure didn't vent the system) - and that was in an electrically heated garage. I didn't NEED to make any liquid water boil. 24 hours at -25 is plenty to allow mere evaporation to work fine. Any minute liquid water that was in there at the beginning was vaporized after that amount of time and the final pump job I did before recharge would address 90% of that. The dessicant pack (system never before opened) is plenty for the couple milligrams of moisture possibly left in the system. Not worth jacking up the cost of the job by 15% to improve on minutely. I'll fess up if it goes bad, but I highly doubt it.
Potentially good tip about the free tools at Autozone though. I forgot about that. My past experience with them has been that 80% of those loaner tools are worn out, but YMMV.
 

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Ah, Mr. Clark. We meet again. I'm still waiting for my "must replace" bolts in my timing belt job to bust too since I scorned replacing them. I appreciate meticulous, but I maintain that some folks overdo it.

It's true that water doesn't boil at -25. But I didn't submerge the stupid truck for crying out loud. The system was exposed to atmosphere for all of 2 hours during the job (the failure didn't vent the system) - and that was in an electrically heated garage. I didn't NEED to make any liquid water boil. 24 hours at -25 is plenty to allow mere evaporation to work fine. Any minute liquid water that was in there at the beginning was vaporized after that amount of time and the final pump job I did before recharge would address 90% of that. The dessicant pack (system never before opened) is plenty for the couple milligrams of moisture possibly left in the system. Not worth jacking up the cost of the job by 15% to improve on minutely. I'll fess up if it goes bad, but I highly doubt it.
Potentially good tip about the free tools at Autozone though. I forgot about that. My past experience with them has been that 80% of those loaner tools are worn out, but YMMV.
As you can tell, I obviously don't hold a grudge and my memory is good but short. Apparently the same can't be said for you. Thanks for calling me out...it's always appreciated. /Sarcasm.

As for the timing belt bolts that are recommended to be replaced, I didn't make it up. It's written in the service manual. I don't know that I ever said they would break if you didn't replace them, but whatever. They are relatively low torque so I don't think the issue is breakage but probably more whatever the thread locker is that they put on them. Admittedly, that's speculation since the service manual doesn't say why...it just says "replace." You can do as you like. I'm betting most people don't replace them.

Your "theory" on the moisture in the system, unfortunately for you, doesn't hold water (no pun intended.) If the system is sitting at -25" but is just closed off then where is the moisture going? It's evaporated but still in the system. It's just sitting in the system since you're not removing all of it. Most of the time the moisture in the system is all in the form of vapor to begin with but you can have condensed vapor in parts of the system that will not come out right away and will need to be "boiled" off. If it wasn't necessary to bring a system down to 29" or more, and let it run that way for 30 minutes, then nobody would do it as it takes a lot of time to do that.

I just didn't want anyone to follow your lead. It's a hack fix on your AC system and while you may get away with it, at least for a while, it's a good way to ruin an AC system.
 

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I just didn't want anyone to follow your lead. It's a hack fix on your AC system and while you may get away with it, at least for a while, it's a good way to ruin an AC system.
John, come on now . . . open for 2 hours in a heated garage? Seriously, how much moisture is going to get in there? Now if the system had been left open for a year, with the vehicle sitting outside, then you have a valid point. I appreciate that you're trying to ensure people don't do something incorrectly, but I've been doing automotive A/C work myself since the early 1980s and what was described above was FAR from being a hack job.

A hack job is somebody going down to the auto parts store and buying one of those "miracle in a can" A/C recharge kits (that contains leak stop, leak indicator dye, refrigerant and sometimes even oil) and pumping as much of it into their system as they can get in without doing anything else. I just watched a neighbor do that a couple of months ago.
 

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Yes, a hack job description might be a bit strong. Yes, at least he got most of the air out. He might get lucky and it will last. In my opinion, the system is too costly for a shortcut like that. Having had to clean AC systems from destroyed compressors it's a job that is not very fun, especially for the DIY'er. Yes, it's worse to add that crap in a can but people should not think this is the right way to do an AC repair and expect it to last. As soon as you open it the system is exposed. Would I replace the receiver/dryer just for that quick exposure? Probably not. However, humidity in the air is usually around 50% or more in most places and warm air holds more moisture than cold air so the warmer it is, the more moisture there can be. I just wouldn't recommend anyone do it this way. You definitely want it pumped down to a strong vacuum, allowing any moisture to be pumped out, not just sitting in there under the vacuum. The only reason for letting a system sit under vacuum is to check for leaks. The sitting doesn't help with moisture removal.
 

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It's been a rather long time since high school physics and gas law, but here's my answer.
If there is NO liquid water in the system, then once you reach a certain measurement of vacuum and the running pump is just holding that level, then it is not actually evacuating any mass. If it's not evacuating mass, then it's not removing any remaining water vapor. Basic conservation of mass.
Holding vacuum in a closed system over time CAN turn liquid water into vapor. In my case, that would have manifested as a drop in pressure. In the case of a motor pump holding constant gage vacuum, that extra water mass would be evacuated. Since my vacuum reading didn't drop any in 20 hours, it's reasonable to conclude that there was no liquid water in the system at the time I applied vacuum. So the difference between my vacuum pressure and the 'proper' one is limited. If we knew the total volume of the system and the humidity of the air in starting conditions we could calculate the actual water mass difference between -25 and -30. But I didn't bother because the answer is clearly: negligible and well within the desiccant capacity.
 

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It's been a rather long time since high school physics and gas law, but here's my answer.
If there is NO liquid water in the system, then once you reach a certain measurement of vacuum and the running pump is just holding that level, then it is not actually evacuating any mass. If it's not evacuating mass, then it's not removing any remaining water vapor. Basic conservation of mass.
Holding vacuum in a closed system over time CAN turn liquid water into vapor. In my case, that would have manifested as a drop in pressure. In the case of a motor pump holding constant gage vacuum, that extra water mass would be evacuated. Since my vacuum reading didn't drop any in 20 hours, it's reasonable to conclude that there was no liquid water in the system at the time I applied vacuum. So the difference between my vacuum pressure and the 'proper' one is limited. If we knew the total volume of the system and the humidity of the air in starting conditions we could calculate the actual water mass difference between -25 and -30. But I didn't bother because the answer is clearly: negligible and well within the desiccant capacity.
manualman,

From physics class you would know the relationship of pressure, volume and temperature on a gas. You would also know that air contains a lot of water. You can see the water condense on the can of refrigerant when it cools. The same thing happens to the inside of the system when you open it up. Evaporation cooling is how the system works, and it works well. The massive pressure reduction of opening the system has the offsetting relationship of reducing the temperature because pressure and temp are on opposite sides of the equation (and we can ignore volume because the size of the system is constant. The systems cools quickly, then as it warms back up air is drawn and water vapor condenses on all those cool surfaces. The air entering just the drier desiccant is usually enough to reduce a large capacity of the desiccant, which is why they want you to replace it when you open the system.

The reason that professionals use a good vacuum pump (one that can drawn down to very low levels) is because water only changes back to air at very low vacuum levels at room temperature. Very much lower vacuum levels than any hand pump can reach. The reason the vacuum remains the same is because no water is evaporated. If you evacuated the system and back filled with pure nitrogen and let the system stabilize slowly and keep purging pressure slowly until the system was at equilibrium with temp/pressure of the ambient air, you could possibly assume that little water vapor entered the system if you capped every part of the system as soon as it was opened, but there are still parts of the system that are open to the air, particularly the parts you replace. Generally only the HVAC pros purge with nitrogen on larger systems, and they still vacuum it down carefully afterwards.

In large vacuum chambers it is very hard to get enough vacuum to get all the water out, so they compromise by using a very cold hvac system system in one corner of the chamber to condense the water there and keep it controlled.
 

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Why not rent a vacuum pump from autozone for free, buy three cans of refrigerant, and do it right? If you're DIY it's cheap. If I had a shop that would do that for me for $60 I'd gladly pay it. Around here an AC service is $150.
 

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CNN, once again, you have saved me time and money. I'll be replacing the compressor this weekend.

My question is about the air gap. Is it necessary to adjust it down to 0.3mm? What will happen if I leave it at the factory standard? If it is necessary, how do I adjust it?
 
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