A/C puzzle
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5th Wheeling
Joined: May 2021
Posts: 37
Likes: 13
A/C puzzle
I am looking for expert advise.
The label in my Ex states maximum operating charge of R-134a is 1.94kg (4lb 4oz), and 414cc (14 fl oz) of oil.
We replaced everything but the rear evaporator.
The new compressor came with 5.25 fl oz of PAG, and we added 8 fl oz into the system.
My issue is that we only could "fit" 1.7 kg (3 lb 12oz) of R-134.
We stopped adding refrigerant because the pressures went above what I though they should be.
The external temp was 95, humidity around 75%, low pressure side was 65 with high side of 325.
Air vent temp got stable at 63 F, too high for what I understand, but 30F less than external, so I am unsure if it was proper. Rear AC air vent is stable at 65F.
I know that a clogged or deficient condenser, or overcharging, can cause high readings on both sides, but it is all new and I am sure of the amount of refrigerant loaded.
Should I disregard the factory label, bring it back to a shop and have refrigerant evacd until pressures stabilize around 45/310.
Or should we load the remaining refrigerant and bring it to spec?
The label in my Ex states maximum operating charge of R-134a is 1.94kg (4lb 4oz), and 414cc (14 fl oz) of oil.
We replaced everything but the rear evaporator.
The new compressor came with 5.25 fl oz of PAG, and we added 8 fl oz into the system.
My issue is that we only could "fit" 1.7 kg (3 lb 12oz) of R-134.
We stopped adding refrigerant because the pressures went above what I though they should be.
The external temp was 95, humidity around 75%, low pressure side was 65 with high side of 325.
Air vent temp got stable at 63 F, too high for what I understand, but 30F less than external, so I am unsure if it was proper. Rear AC air vent is stable at 65F.
I know that a clogged or deficient condenser, or overcharging, can cause high readings on both sides, but it is all new and I am sure of the amount of refrigerant loaded.
Should I disregard the factory label, bring it back to a shop and have refrigerant evacd until pressures stabilize around 45/310.
Or should we load the remaining refrigerant and bring it to spec?
Cargo Master
Joined: Nov 2017
Posts: 3,110
Likes: 540
From: Rock Hill, SC
Technically you can almost as much Freon as you want, until one of two occurrences are met, High pressure switch trips, or the compressor blow off opens.
The Ford OE compressors do not come with oil, (not sure what aftermarket are doing) and I don't see that they have a sump to hold any oil anyway. (as I observed from my recent replacement) The accumulator/drier seems to be the sump for this system with an oil siphon in the bottom.
The OE Ford replacement condenser is slightly different than was originally installed at the factory, calling for a slightly smaller charge. The new Ford condenser comes with a new charge rating sticker.
The amount of oil you add to the system is determined by the amount of oil you removed as measured from each component. Or per the service book a predetermined amount added for each new part replaced.
Since "everything" is no longer avail, you would be re-using the rear under-body line set, and some select other hoses, which all hold some small amount of oil, unless a liquid flush was done.
The system needs to be evacuated to the lowest micron possible, or 32 In Hg.
Your pressures are high, you may have drawn some sort of debris through the system and to the orifice screen.
The Ford OE compressors do not come with oil, (not sure what aftermarket are doing) and I don't see that they have a sump to hold any oil anyway. (as I observed from my recent replacement) The accumulator/drier seems to be the sump for this system with an oil siphon in the bottom.
The OE Ford replacement condenser is slightly different than was originally installed at the factory, calling for a slightly smaller charge. The new Ford condenser comes with a new charge rating sticker.
The amount of oil you add to the system is determined by the amount of oil you removed as measured from each component. Or per the service book a predetermined amount added for each new part replaced.
Since "everything" is no longer avail, you would be re-using the rear under-body line set, and some select other hoses, which all hold some small amount of oil, unless a liquid flush was done.
The system needs to be evacuated to the lowest micron possible, or 32 In Hg.
Your pressures are high, you may have drawn some sort of debris through the system and to the orifice screen.
Thread Starter
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5th Wheeling
Joined: May 2021
Posts: 37
Likes: 13
Thank you.
Yes, I used the word "everything" quite loosely here. And most likely I underestimated the amount of residual oil in the lines, so maybe there is too much oil.
It was hard enough to find a half decent AC shop around me to evacuate the system, and didn't get anything from them telling me what was recovered, just a $120 bill.
I did get a motorcraft compressor (ycc489) and it did come with a sticker stating that an amount of oil was there ( I don't remember the exact amount, something like 5 oz, I think) supposedly to be new. Looks identical to what was in my ex.
I got condenser, evaporator, and receiver from four seasons. Sensors, Orifice tube and exp valve are motorcraft.
So, I believe your recommendation is to flush and evac the system again.
I would love to know if there is a recommendation for shop in Broward County, FL, that could do a liquid flush and reoil/recharge the whole system. The only thing that seems to be worse than AC mechanics in South Florida are boat mechanics...
Thank you very much.
Yes, I used the word "everything" quite loosely here. And most likely I underestimated the amount of residual oil in the lines, so maybe there is too much oil.
It was hard enough to find a half decent AC shop around me to evacuate the system, and didn't get anything from them telling me what was recovered, just a $120 bill.
I did get a motorcraft compressor (ycc489) and it did come with a sticker stating that an amount of oil was there ( I don't remember the exact amount, something like 5 oz, I think) supposedly to be new. Looks identical to what was in my ex.
I got condenser, evaporator, and receiver from four seasons. Sensors, Orifice tube and exp valve are motorcraft.
So, I believe your recommendation is to flush and evac the system again.
I would love to know if there is a recommendation for shop in Broward County, FL, that could do a liquid flush and reoil/recharge the whole system. The only thing that seems to be worse than AC mechanics in South Florida are boat mechanics...
Thank you very much.
Laughing Gas
Joined: Nov 2014
Posts: 1,108
Likes: 23
You do have 2 expansion valves-front and rear. When the rear one went bad, I couldn't get the rear air cold. I have no clue if an expansion valve would play any role in your particular problem. I just saw that you said Valve and not valves..FWIW
I bought an evacuation pump off of eBay. At the time, I was so far out in the sticks that going to an AC mechanic created a lot of logistical problems. I ended up evacuating it twice-perhaps unnecessarily . It took forever to get a proper freon charge loaded. Part of that was due to the fact that I'd never done it before and the first set of guages I bought were crap. The second set that worked correctly made it a he!! of a lot easier. When it got close on pressures, I just used the temps at the vent to tweak the amount added.
I bought an evacuation pump off of eBay. At the time, I was so far out in the sticks that going to an AC mechanic created a lot of logistical problems. I ended up evacuating it twice-perhaps unnecessarily . It took forever to get a proper freon charge loaded. Part of that was due to the fact that I'd never done it before and the first set of guages I bought were crap. The second set that worked correctly made it a he!! of a lot easier. When it got close on pressures, I just used the temps at the vent to tweak the amount added.
Thread Starter
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5th Wheeling
Joined: May 2021
Posts: 37
Likes: 13
As per 01_Excursion explanation above, I believe I have contamination in the circuit, as I did not had it flushed. I think the contamination includes quite some oil, and when I added to the system, les space was left for the refrigerant.
For whatever reason, the Ex has an orifice tube in the front circuit and an expansion valve on the rear circuit. I replaced both.
I wish I knew enough to know why Ford decided for two different systems in this truck.
I am looking for a shop to evacuate and flush the system, to make sure it is clean. Then we can vacuum and fill it again.
If that does not make it, I will have the condenser replaced by an OEM, most likely a motorcraft. There must be a reason why it costs 3 times more than others...
As the rear evaporator was very clean, I don't think it is a factor on my issue, even thinking it is very easy to replace.
For whatever reason, the Ex has an orifice tube in the front circuit and an expansion valve on the rear circuit. I replaced both.
I wish I knew enough to know why Ford decided for two different systems in this truck.
I am looking for a shop to evacuate and flush the system, to make sure it is clean. Then we can vacuum and fill it again.
If that does not make it, I will have the condenser replaced by an OEM, most likely a motorcraft. There must be a reason why it costs 3 times more than others...
As the rear evaporator was very clean, I don't think it is a factor on my issue, even thinking it is very easy to replace.
Laughing Gas
Joined: Nov 2014
Posts: 1,108
Likes: 23
If you want to know what a reasonable cost for the condenser is , go to fordpartsgiant.com where you can see the list price versus the retail price. Having seen what the dealer charged for parts after 3 deer strikes (fortunately to the insurance company), it was a bit sickening. Granted they have to make a profit to meet overhead but sometimes things were double the price.
Cargo Master
Joined: Nov 2017
Posts: 3,110
Likes: 540
From: Rock Hill, SC
What year and engine is this Excursion? If you are a V-10, that compressor may very well come with oil. The compressor for the 7.3 does not.
Excursions have only 1 TXV (Thermal Expansion Valve), which is located in the rear coil. The front is metered by a fixed orifice/strainer.
The purpose of the TXV in the rear is to be able to control the flow of refrigerant to the rear coil based on the heat load demand combined with fan speed. Since the compressor has to be running therefore always pumping Freon when it is, the rear "has" to have a way to slow or shut down the flow of refrigerant when the coil gets cold enough, or you are not using the rear at all. So if both coils used a TXV, and for some reason the rear was off, the front had met temp, you would create a compressor pressure problem. If the rear had no way to shut down at all, the coil would eventually freeze/ice over. So instead of using 2 compressors, the TXV was used in the rear. Years ago, 1970's Ford used a Suction Throttling Valve to regulate Freon through the coil. Newer technology brought about the TXV, which is more compact and pretty dependable.
Excursions have only 1 TXV (Thermal Expansion Valve), which is located in the rear coil. The front is metered by a fixed orifice/strainer.
The purpose of the TXV in the rear is to be able to control the flow of refrigerant to the rear coil based on the heat load demand combined with fan speed. Since the compressor has to be running therefore always pumping Freon when it is, the rear "has" to have a way to slow or shut down the flow of refrigerant when the coil gets cold enough, or you are not using the rear at all. So if both coils used a TXV, and for some reason the rear was off, the front had met temp, you would create a compressor pressure problem. If the rear had no way to shut down at all, the coil would eventually freeze/ice over. So instead of using 2 compressors, the TXV was used in the rear. Years ago, 1970's Ford used a Suction Throttling Valve to regulate Freon through the coil. Newer technology brought about the TXV, which is more compact and pretty dependable.
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Laughing Gas
Joined: Nov 2014
Posts: 1,108
Likes: 23
My bad-01 is absolutely right. I remember now thinking when I had it broken down so I thought I should replace a front expansion valve but it all revolved around an orifice tube. It was 4 1/2 years ago. Glad he caught it.
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