I'm fairly new at the air conditioning repair aspects, but a pretty skilled amateur mechanic, with LOTS of tools

Subject car is a 2003 Jaguar XKR convertible that I've had for 11 months. A/C has worked well up until recently. Recently, the temperature wouldn't get below 74 deg when outside air temperature is upper 80's. I ran the A/C diagnostic just to see what it said. I forget the code that it threw, but it indicated that the refrigerant level was low. Okay, that confirms the initial diagnosis. I have gauges and refrigerant. I've done some A/C work in the past, namely replacing just about everything on my old Pontiac and successfully recharging with R-152a. I added a few ounces of R-134a into the Jaguar this morning, but the low-side pressure was up around 90 psi. I thought maybe I had added too much, but since I couldn't be sure, I vacuumed the system down for a few minutes and started over. System requires 1 lb 7 oz, or 23 ounces, just shy of two 12 oz cans. (Tractor Supply, $9.99 each). First can went in okay, but the second can didn't want to all go in. I got about 5 oz of it in, and it just wouldn't suck any more in. Thought maybe I was doing something wrong, and it was getting hot, and I was working in the sun (don't something that you should do), so I wrapped it up for the morning.

Later in the morning, I drove the car 4 miles to the store. A/C was blowing at 74 deg, but after a few minutes in the store, on the return trip, a/c was only getting down to 80 deg (about 88 deg outside air temp).

Before dusk, it had cooled down enough that I could try again. I checked the static pressure before I started the car. It was 90-92 deg in my garage, and the static pressure was 110 psi, so in the ballpark (I think I need to calibrate my thermometers). I moved outside, where the temperature was about 82 deg, so my target was 40-45 low side, 175-250 high side (Jaguar values for 80-85 deg). I was able to get a few more ounces of refrigerant into the system, and am maybe 2 oz short right now. When I closed the valve on the can to check the system pressure, the high side was about 175 psi, and the low side was 90 psi. I think the blue low-side knob was still open. It took maybe 10 minutes for it to creep down, and finally stopped at 27 psi low side, 175 psi high side. A/C was blowing at 84 deg, and it was 82 deg outside.

Now, I've thought about it for a couple hours. When I fit the quick-connects onto the Schrader ports, I don't bottom them out. I only tighten them down until there is a reading on the gauge, then a little bit. I wonder if maybe I didn't crank the low side down far enough, and that is why it was difficult to get refrigerant in, and the pressure took so long to drop. Is that possible? What else could be causing the refrigerant so long to flow in, and the pressure to take so long to drop?

One other little tip that I'll throw out for you guys that I picked up was that when you remove the quick-connects, 'blip' the Schrader valve to clear it out of any dirt. My high side was leaking when I pulled it off this morning, so I 'blipped' it, and it stopped. It didn't seem to me leaking this evening.

And still, if I'm only a couple ounces short, I'd think I'd get lower temperatures out of the vent. A/C self-diagnostic is not throwing any codes right now. While I've typed this, I'm wondering if maybe I have a mixer valve problem that is introducing air from the heater into the A/C stream. Any other ideas on diagnostic tricks?

Thanks for the help,
Bill

EDIT: The plot thickens. I just checked my thermometers in a glass of ice water. One was reading 5 deg high, the other over 10 deg high. It's a single-point calibration, and I'm not sure which one I used to measure which temperature. Guess I try again tomorrow.

 

Took the car out tonight, but hesitantly. It was 91-92 deg outside, but the A/C was blowing cold, like 62-67 deg, so a 25-30 deg split. Decent performance, considering I'm a bit low on refrigerant and we have high humidity, which if I remember correctly adversely affects the cooling capacity. It should be colder though. I took my Grand Prix out and it was blowing at 30 deg.

I can't explain it, but I guess we can mark this one as almost fixed. I'll probably try to get a little more refrigerant into her, as I know that she is a couple ounces low.

 

Well, looks like we don't have any A/C experts here that can help me, so I'll be turning this into a blog. Like I said, I'm a novice at this, so I'm just learning. I guess we will learn together, and I'll post things here to maybe help the next guy.

Worked on the AC again last evening. Outside Air Temperature (OAT) was 80 deg, so I'd expect to see static pressure of 86.8 psi.I saw 83-85 psi (It went up to 85 from 83 when I first connected the gauges). I was about 2-3 oz low on refrigerant, based on that I had previously vacuumed the system down and then added. After starting the car and letting the pressure settle, I saw about 50/165 psi (low/high side). I was able to get a couple more ounces of R-134a into the system, but when I shut off that flow and checked the pressure, the pressures were at 90/150. Target was 40/175-210 psi.

When I had opened the tap to get more R-134a into the system, the pressure had risen to around 90 psi (I'm not sure exactly what it was), which must be the can pressure. It looks like the longer the system ran, the higher the low side pressure was, and it eventually reached about 90 psi, the can pressure. That would explain why I couldn't get all of the R-134a into the system. There wasn't a pressure differential to cause the flow. When I finished, the temperature of the air coming out of the vents was 68 deg. It cools the car down, but it's still not acceptable.

So, I'm now scratching my noggin to resolve why the pressure rises over time. Sounds like something isn't working correctly.

I've also remember that the previous owner (the only owner besides me) had the car into the dealer in 2017 and 2018 (in the summer) for A/C work. That was reported in the Carfax report, but exactly what was done is not specified. I would like to see the servicing dealer records (Jaguar dealer in NYC) to find out what they did, but living in Orlando, that is probably not going to happen. It apparently worked for 4 years, and is now back. Did they fix something, or is it a mystery that comes up every summer?

 

Is the name of that NYC dealership displayed on your Carfax records? If so, call them, ask for the service manager, provide the VIN and the date of the A/C service, and ask for the details regarding exactly what they did. Some dealerships will provide the information you request and some will not, but it is certainly worth a phone call to find out....

 

Thanks. Good idea. I sent them a message through their website. Thought I might be more likely to get a response than from a phone call.

 

When I was researching a car some distance away, I had good luck with phone calls. Just make sure to call outside of the busy time when customers are dropping cars off or picking them up. Right before lunch time seem to do it. The last few digits of the VIN were generally enough for them to search their system and pull up service records. Somehow mentioning I was doing research on a prospective purchase seem to get service managers beyond the worry about disclosing personal information or the call being about a complaint on a past job.

 

You are more likely to get a favorable response with a phone call rather than an e-mail or website message....

 

To my superficial knowledge (YouTube videos), the more complete service on a system of unknown history requires applying vacuum for quite a while (30 min?) to evacuate whatever is in there. For all you know, there is excess oil in there that needs time to evacuate. Then there was a "test" to check that the vacuum could be maintained, checking for leaks.

 

You are correct, but one would normally only apply a vacuum for an extended period of time for a system that has not been operational for some time, or has been opened for replacement of parts. You would also do that if you suspected a leak, and wanted to verify that the system was leak-free. I read somewhere that AC systems lose approx. 5% of their refrigerant a year, which would amount to about 1 oz per year. After a couple years, system performance could be impacted.

The vacuum allows any moisture present to boil off and be sucked out. However, I was working on a system that had been working relatively well in the past and had not been opened. I believed the system to be low on refrigerant, and had no reason to believe that there was excessive oil present. An extended period under vacuum would tend to remove oil. How much oil is removed is a mystery, and could negatively impact performance. Therefore, I chose to NOT vacuum for an extended period of time.

 

I guess I could find this somewhere but quicker to just ask. What do you need to push to get the A/C diagnostics? I know with various vehicles there are all sorts of key press combinations that will give you codes that show up on climate control panel or elsewhere but don't know what tricks are available on my 2005 XKR.

 

To check for error codes in the Climate Control System with the internal diagnostics via the ‘Panel Codes’

1. Ignition off - hold down AUTO and RECIRCULATION buttons and switch on the ignition

2. press AUTO button - if ZERO shows, there's no stored error codes

3. press FACE button repeatedly to scroll through stored fault codes

4. press FACE and HEATED REAR WINDOW buttons together to clear a fault code.

5. Repeat step 4 if there's more than one code

6. press FAN button to exit Interrogation Procedure

 

here are the codes

 

You are the apparent Jaguar XK8 a/c expert!

So, I'll ask, if the a/c system seems to be performing well, but just a tad low on cooling power, can one just top it off through the low pressure outlet using an auto parts store bought gauge and connector?

I'm really reticent to do anything more involved in fear that I might mess up what is a pretty good thing. Just want to get a little bump in performance, given that I've never touched the a/c in seven years of ('97 XK8 coupe) ownership.

 

Wait, WHA...???? I'm the A/C expert? I'm just a novice.

In theory, if there is nothing wrong with your A/C system, then adding a bit of refrigerant to it should help. I'm going to guess that you don't have a set of A/C gauges, but have or would buy the refill can with the built-in gauge. Before adding refrigerant, you would probably want to check the static pressure. This site (https://ricksfreeautorepairadvice.co...ssure-reading/) (also attached) provides information on that. In theory, your A/C system is a COMPLETELY closed system, nothing entering, nothing leaving. However, in the real world, that probably isn't true. These A/C fittings have a SAE acceptable leakage rate of 1/4 ounce of refrigerant per year per fitting. That does not sound like a lot, but the average vehicle has 8 fittings. This means that you are losing 2 ounces of refrigerant per year. It is recommended that you service your air conditioning every 2 years.

I don't use those cans from the auto parts stores, but I understand that some of them might contain other things, such as sealant. NO! No sealant. You only want R-134a. If you have other cars and/or expect to be doing more A/C work, you might want to think about a set of gauges. The additional cost over that changed by a parts store for the A/C cans with the built-in gauges might be acceptable.

 

ONe quick note. When I install R134a, I put the can in a bath of hot water. That increases the pressure in the can to a point above the pressure in the system, and allows the freon to flow. Especially important in hot climates like Vegas.

 

Y'all are amazing!!!

 

hello kind folks,

i'd like to throw in a question here....
first... i see two black caps..one behind the engine (near the throttlebody) and a second on a small canister (dryer?) to the front.
Q: which one is the low pressure side ?

many thx,

max & TRES

 

Low side is near the firewall, behind the air duct. High side is on top of the drier.

 

Do these cars have expansion valves?
If so, where?
Just wondering.

 

They do, buried in the dash. HUGE job to replace, but I understand they rarely go bad.