Dear Forum,

My Air Conditioning is working - After a fashion?

About a year ago I had it charged up and it was stunning....For a while!
However, it appears to leak down to a point whereby it continues to work okay-ish, but not as effectively; it does not get any worse than at this point? We are back in the 30's C here again....
Before I take it (and my wallet) to an Air Conditioning Expert, has anyone else experienced this?

 

You should have the system vacuum tested first. If there is no leak, recharge with gas and keep the A/C in auto at all times.

 

Seems like all the Jags I've owned lost freon, One was actually a hose at right rear of engine burned by EGR pipe. Being a cheap old ------ I just throw a can of freon in when cooling diminishes. Freon can be bought on Ebay for about $5 a can and a recharge kit from your auto parts store will work just fine. Its pretty hard to overcharge with this procedure, just cant get any more in. I'm sure this post is going to upset the purists but I see no reason to pay big money to a shop. Leak detectors are also reasonable on Ebay or Harbor Freight, although I haven't has much success with them.

 

Hi EsRay,

There are many possible causes of insufficient cooling, and low refrigerant is just one of them. You can certainly add refrigerant yourself (the correct refrigerant is R134a, not Freon (R12), which was banned in 1996). However, I have to respectfully disagree with Terrific on one point: it can be easy to overcharge the system with refrigerant because it may inhale more than is correct for optimum performance and protection of the compressor. The 12 ounce cans of R134a can be pressurized at up to 60 psi or more, but the correct low-side pressure of your system may only be 30 psi, depending on ambient temperatures, so the can can easily force too much refrigerant into the system.

If you decide to try adding refrigerant, put a thermometer in a center dash vent, let it stabilize, then add a little refrigerant at a time while monitoring the thermometer after the system stabilizes again after each addition. If you get to a point where the temperature begins to climb again, you have overcharged and need to recover some refrigerant into an empty R134a can. It is unlawful to vent refrigerant to the atmosphere. Also, remember that when you add refrigerant you do nothing to remove any air or moisture in the system, nor do you replace any oil that may have been lost through the leak (which is critical for the survival of the compressor).

A good technician can closely judge the proper charge using a pair of manifold gauges (one each for the high- and low-pressure sides of the system), but the best way to ensure the system is properly charged is to recover the refrigerant, vacuum evacuate the system to remove all residual air and moisture and confirm there are no significant leaks, then recharge using the correct amount of refrigerant by weight and oil by volume.

As I mentioned, there are a lot of other issues that can affect cooling performance, such as condenser obstruction (seeds, leaves, mold, etc.), a failed or malfunctioning radiator/condenser fan, problems with any of the sensors (refrigerant pressure, ambient air temp, evaporator temp, solar sensor, and at least a couple of others), a problem with the power supply or control of the variable-displacement compressor (thanks to mhamilton for the education on that), air and/or moisture in the system, problems with blend flaps in the dash/center console, etc.

If you have a scan tool that can read Live Data, you may be able to view the signals from the various sensors to see if any of them is providing an implausible signal.

If your scan tool can read proprietary Jaguar diagnostic trouble codes, it would be worth checking for any B- (Body) or U- (Network) codes that may help narrow down the diagnosis.

Regarding leak detectors, the so-called "leak sniffers" are not worth the money, in my opinion, because it only takes the slightest breeze to render them useless, and typically when you are testing an A/C system the cooling fan is running, so there's always a breeze. Injecting UV dye into the system is often effective. The dye glows under UV/black light and can help locate leak points.

Cheers,

Don

 

Thank you both for your posts.
What do you guys think of this video, please? The kit being used has a pressure gauge which (I guess) could be used to ensure that one does not overcharge the system? I want to try to find out if I have a leak and where it is (obviously cheaply)?
For example, if I have a leaking o-ring, that is something I could easily repair myself and then I will only need to pay to have my system evacuated and refilled professionally?

 

The only way to accurately check pressure is with a set of gauges and an ambient temp/pressure chart. Those auto parts store DIY cans are just shooting in the dark and can cause more problems. Yes, you can repair an O-ring but you'd have to evacuate the system first. If you'll have somebody vacate into vacuum state, leak test, add refrigerant/oil, then you might as well have him do the O-ring too.

 

Thank you; understood.

 

Please, is there already UV dye present in our systems and how easy is it to replace the desiccant?

 

As I said the guys with deep pockets would disagree with me. Of course if there is a detectable leak it will have to be repaired and a vacuum pulled and recharged. i have a dedicated AC outlet temp gauge which has a green area for acceptable cooling temp. Keep in mind that many ACs can only cool about 20 degrees cooled than ambient if very hot outside. Yes that is a very good DIY video. P.S. your car appears identical to mine.

 

Not even deep pockets - So far (three XJ's over 11 years, I have NEVER taken my car to anyone for repair work (YET - there are jobs I would not attempt, nor have resources; tools/lift etc. to perform. For AC refrigerant top-ups, I have to concur with Don - even without a proper set of gauges, just using the simple one you get with consumer refill cans and kits can give you a basic idea, but over charging is not only possible, it is counter-productive.

I have had systems that were quite cold. Then by being greedy and squeezing just a bit more R234a in, the system was warmer. If SOME is good, MORE must be better, right?

Not right. Once you cross the threshold of system capacity you create higher pressure than ideal, and the system flips the compressor off as a safety measure. It does this even more on really hot days - the higher the temp, the higher the pressure - those cheap gauges that come with top-up kits show pressure AND temperature, indicating that you can put more pressure in the system when the ambient temp is cooler. This is scientifically correct, but lacks the ability to fill by weight which is the ONLY way to get the perfect ratio of refrigerant. It IS better than nothing, and can show you when you are in the ballpark.

The negative effect of overfilling is what happens with the pressure valve on the system. This valve will ONLY run the compressor when the pressure is within range, neither too low nor too high. This prevents running the compressor dry and empty and damaging the compressor, or running over pressure and possibly tripping of a major sudden leak (which is not too different from an explosion, minus the flames.) I have experienced one such event with what I think was a pressure relief valve inside the V of a 5.3 liter Jaguar V12. No one got hurt, but my head was about 20 inches from the escaping refrigerant, and I almost needed to wash my shorts afterwards. Dramatic.

I agree that MOST of the time you won't seriously over pressure a system, especially ones that can run at high pressures and it beats melting in the summer, but the more I over fill, the system gets a bit warmer and warmer the more I try to top up. I thought of trying to watch the compressor cycling to get the pressure close to ideal, but a) the compressor on a 4.2 liter X350 is way down there and b) the AC clutch on our cars doen't cycle on and off to regulate the system. Our cars use a "Clutchless Variable Displacement Compressor

- see this short explanation:


Very cool ^ (punny). The only way I know to get the pressure closer to ideal without a set of proper gauges is by putting a thermometer in the center dash vent. With a bit of patience, even without proper tools, you can get close to the coldest temps by tweaking pressures and monitoring results. Avoid venting refrigerant into the open air. 134a is better than R12, but still bad to vent. Also illegal.

EsRay, I doubt you have over pressure since you had it colder and it degraded over time. I wonder if you have a slight leak that blows off high pressure, but is then able to hold a lower pressure. I picture a marginal o-ring that leaks when pressure is high enough to compress it, then holds when less force is applied as with lower pressures. Many of the refill cans have leak sealer in them, and you can get small cans of sealer. I think adding small amounts of combination refrigerant/sealer and checking the temps at the dash vents is a reasonable option to see if you can improve the situation without too much risk.

 

Did you happen to see this?

AC was not working, Accidentally Solved by Releasing Pressure

https://www.jaguarforums.com/forum/x...essure-216385/

Sort of an extreme case of what I was saying about overcharging. I got my XJ8L super cold by slowly releasing some pressure into an empty can of refrigerant, a little at a time. I didn't even break the law by venting into the atmosphere, lol! I'n not saying this is EsRays's issue. But it is worth noting.

 

EsRay, I doubt you have over pressure since you had it colder and it degraded over time. I wonder if you have a slight leak that blows off high pressure, but is then able to hold a lower pressure. I picture a marginal o-ring that leaks when pressure is high enough to compress it, then holds when less force is applied as with lower pressures. Many of the refill cans have leak sealer in them, and you can get small cans of sealer. I think adding small amounts of combination refrigerant/sealer and checking the temps at the dash vents is a reasonable option to see if you can improve the situation without too much risk.[/QUOTE]

I agree; that is exactly what I visualise. Thank you all for your time and posts. I have managed to get a garage near me that does only refrigerant top-ups to agree to help me put some UV dye in my low side (I will provide the dye) and then to put some (a little) increase in pressure to the system so that I can search for what must be a small leak with a UV light over time.

I think this will be cheaper than recharging fully to 35 psi on the low side and then losing much of it finding the leak?

I understand from all your posts that if I find the leak I will then need my system evacuating before fixing the leak and then refilling etc.
Does this sound okay, please?

 

I might try this as the UV dye. You might get lucky is it's a crushed o-ring that this will resolve...


As for 134a, even that can have SOME leak sealer as well. I have always used 134a with some leak seal as a preventative. I dont believe that it is harmful I small quantities.

 

You guys are right on all counts. But just saying I've gotten thru 11 Jags without paying for a professional charge.

 

Wouldn't a cheap vacuum pump from Harbor Freight with the right amount of 134a work?
After fixing the leak, & holding vacuum for 30 min of course.

 

I don't see why not. He needs to check about compressor lubricant too. I remember when I replaced the condenser and filter drier on my XJ6 it used a Castrol oil.

 

Unfortunately we do not have Harbor Freight or anything like it here in Dubai.....

 

Just a thought about Harbor's vacuum pump;
They are not that much, even if shipped to you.
Compared to price of paying to have it done at a garage.
By someone who may or not do a good job.
After using a tool a time or two, it has paid for itself.
Ready for the next victim, & those are profit saved in my pocket.

 

Thanks Wingrider.
I took a look at their website. You're right, the pump is very reasonably priced for the Natives! However, the price doubles for me, even assuming they ship to the UAE!
It appears to me that I would also need a compressor and the hoses to attach to my service ports?

I really want to try to find out what is leaking and then plan my next move? I have been quoted AED 250 (USD 70) for Aircon Service and a further AED 150 ( USD 42) for recharging. But of course if or when they find my leak, what will be the cost for them to repair it....??

I guess what I really need is an all-in-one; gas, sealer and dye all in the one can with connector?

I have looked at the following:

1 https://www.desertcart.ae/products/4...ye-1-oz-bottle
2 https://www.desertcart.ae/products/1...34-a-18-ounces (no dye or Stop Leak)
3 https://www.desertcart.ae/products/1...p-leak-12-3-oz (No dye)
4 https://www.desertcart.ae/products/1...nd-gauge-18-oz
5

 

Terrific, Blairware I know that Don & Co are right?

But I will be leaving my beautiful LHD Jaguar behind when I leave Dubai in the next two or three years; so when I decide on what is right, my heart says do it properly but common sense says do it cheaply? I have OEM'd everything under the bonnet, but I replaced an Airshock with one from Aerosus https://aerosus.com/jaguar/xj-series...uspension.html
I know I have lost CATS on that shock, but who is going to pay me what the car is really worth if I spend a small fortune on 4 OEM shocks?