1987 series 3 XJ6 new air conditoning problem

Some of you may remember two years ago the compressor failed on this car, at which time I found a competent shop which converted the system to R134A and installed a new modern Four Seasons brand compressor as well as new ‘O’ rings on all connections. As we all know, R134a does not run as cool as R12, but, after cleaning the fins on the radiator and condenser, at least an acceptable level of cooling has been obtained. During these last two years, the car has been driven only 3000 miles, always driven with a/c on at least ten miles every seven to ten days. When I drove the car ten days ago, as I pulled in to a gas station , I thought I noticed the compressor seemed louder than I remember. At the time I thought maybe it sounded louder because I opened the window slightly. I filled the car, drove home, and thought nothing more about it. Yesterday, I took the car out for a drive. It was a ‘mild’ warm day, with temperature outside in the mid 70’s (F), with more humidity in the air than I would like. On the first mile of the drive, the air conditioner was blowing nice cold dry air. Suddenly, over the next few miles of driving, the air became gradually less cool. . I pulled over to the side of the road and removed the center console ‘cheek’ panel to make sure the a/c amplifier which I’d replaced several years ago, was properly connected. It was. I went back inside the car and turned the a/c on and off several times at which time I noted the RPM’s on the tach remained constant, knowing they should drop when the a/c is turned on. Then I remembered the incident several weeks ago when I’d thought the compressor seemed louder than usual. At this point, it seems to me the ‘new’, two years old with less than 3000 miles on it, Four Seasons compressor, has failed. If my theory makes sense to any of you, the next question is, why should a practically new unit go bad? What do I do now? I’ll call the shop which installed this unit for me two years ago on Monday. I had purchased the Four Seasons compressor from ‘Rock Auto’, and, at the time, because the shop installed my unit, they told me (and I don’t blame them), they would not give me a warranty. If in fact the compressor is the culprit here, even if it costs a bit more, I’d tell the shop to obtain the replacement unit, but give me a warranty. Even so, I think most shops only give a 12 month warranty anyhow, so in my case, this would not have made a difference. At this point, do I consider another Four Seasons brand compressor, or should I ask the shop if they would recommend a different brand? The Apco brand compressor which failed two years go lasted me from 2008 till 2019. Any advice would be welcome. Thank you
Mel R.

Failures are failures, Mel - they may come out of the blue; ‘ours is not to reason why’, but to find and remedy…

First step is to verify that the facia vents are open - signifying that the system is actually in ‘cool’ mode. Next; does the compressor actually engage - distinctive click as the clutch engages. With no click; check for power at the clutch ‘no power’ - jumpwire to verify that the clutch click. If power; check/jump ground connection - if no power; check thermal fuse, if fitted…

There are three power controls; the function switch, the Ranco thermostat, the pressure switch and the thermal switch - as fitted. They are difficult to asses, but the Ranco and pressure switch may be jumped - if tripped/failed…

With the compressor engaged; check sight glass at the end of the receiver/drier - occasional air bubbles indicate a fully charged system. Stream of bubbles; refrigerant low - no bubbles; system empty or full. Oily streaks; system empty, possible compressor fault…

Certainly, your compressor may have failed - but don’t immediately jump to that conclusion without some proof. Noise may be from the compressor clutch failing - no/little drop in idle rpms when compressor engages may be an empty system due to leaks…

The shop will of course easily identify the problem - and remedy, at cost…:slight_smile:

xj6 85 Sov Europe (UK/NZ)

Thank you for your reply, Frank.
As far as the first step you describe, yes, the facia vents are open and blowing air full force, but not cold air now. Turning the a/c on and off results in no difference in RPM readings on the tachometer, the compressor is definitely not engaging. What intrigues me most about your reply is your comment, “noise may be from the compressor clutch failing.” Looking back on my recent experiences , I’m leaning towards the possibility the compressor clutch may indeed be the culprit here. When I drove the car a week and a half ago, the compressor was definitely louder than it should be, and when I turned off the a/c, the noise subsided. When I turned the a/c on once again, the noise returned. By the time I reached home, the noise wasn’t as prevalent. When I drove the car two days ago, I forgot about the noise from ten days earlier, perhaps attributing it to just another ‘glitch’ which we know these cars are prone to present to us. So, when I started driving the car two days ago, I turned the a/c on as I began my journey. There was no unusual noise, and the a/c was blowing nice and cold, cold as one could hope for with R134A. After driving several miles, the ‘cold’ factor’ of the air coming out of the vents began to diminish, until the air coming out of the center vents was simply the same temperature as the air temperature outside. Like I said earlier, when I turned the a/c on and off at that point, tachometer showed no change in engine RPM’s. My theory is, if ten days earlier, when the noise began, a leak had developed, or the compressor itself had completely failed, I would not have enjoyed the brief two mile drive two days ago with the a/c blowing nice cold air. I’ll have to visit the a/c shop to confirm my suspicions, but my final question to you is, if a failing clutch is the culprit here, which may have been ‘on its way out’ ten days ago and finally failed completely two days ago, can it, in fact, be replaced on the compressor without having to remove compressor from the car , and is it then possible, when the shop measures levels of R134 in the system, it may not have leaked at all? If so, why would a clutch fail after only two years and 3000 miles of use? I suppose I’ll have to leave it to the shop technicians to find an answer to that one, but any further thoughts you may have would be welcome. Thanks

Mel R.

When the original compressor in my 85 F150 failed it sis so with a bang!!! I cut the bet to allow the engine to run and drive home.

In addition to other stuff. if it is a compressor failure, I would suspect a coolant leak and loss of lubrication.

Also, so many other things as said.

Can you jump the compressor clutch and see if the clutch engages.

And, arbitrarily just charge the system.

OH, one other, mine was extremely sensitive to vacuum. Loss of it and hot air. Lost engine, never tracked that one down… My unit remains sans charge…

A failed clutch happened to me, Mel. I did not really notice anything untoward; but all of a sudden it was a racket like the engine was falling apart - but the diagnosis was easy; the pulley was wobbling around.

In my case; it was the original compressor, some twenty years old, and while the shop could replace the clutch only; they suggested replacing the compressor complete. Replacing the compressor likely required compressor out - shops do not like keyhole surgery…:slight_smile:

The crucial point is whether the clutch has power and indeed clicks to signify engaging. If so; no drop in idle signifies lost refrigerant. Observed over time, the loss may be noticeable by gradually lessening idle drop - but it requires some attention to such a detail. The best method is to check the sight glass - it may give an earlier warning. You can of course also check the pulley for play, like on a road wheel - and there should be none.

The shop will sort it all out, at cost. In my case, the system leaked down quite quickly, then again more slowly - and then again; a minute leak, difficult to locate. However, being a reputable shop, they unquestionably assessed it as their fault - and I paid nothing beyond the original replacement work…

In other words; while your shop may not have offered a warranty regarding the compressor - but their work itself might be a different matter. In any case; I do not consider myself competent to handle AC - except the electrics…:slight_smile:

My guess; loss of refrigerant - but I may be wrong…

xj6 85 Sov Europe (UK/NZ)

I made an appointment to have the shop evaluate the situation at the end of the week. I’ll let you know what happens. Thanks
Mel R

I drove to the shop over the weekend and, overall, I’m pleased I chose to do business with this shop even though it’s located 15 miles from home and was highly recommended to me by a local Jag club member. First, the owner had one of his assistants hook up the pressure gauges and hoses to the car, and gave me the news I was hoping to hear, that the system did not have any leaks, and, in fact, is as full as R134A as the day the car left the shop two years ago. So, why was the compressor not engaging? After vaccuming out all the R134A, and troubleshooting various wires and connections, the fault was found., that being the failure of one of the wires leading to the compressor. After repairing the offending wire and refilling the system with the R134A vaccuumed out earlier, the a/c system came back to life. He took the car for a test drive, and noted when he had to stop at a red traffic light for more than a minute, the a/c ran less cool. He brought it back in to the shop and hooked up the gauges once again. he said when the engine was idling low, pressure on the ‘low’ side gauge ran a bit high, but once he revved the engine above 1500 RPM, pressure readings came up normal where they should be. He couldn’t give me a definitive answer as to why this was taking place, suggesting perhaps the compressor was running ‘weak.’ I reminded him the system performed the same way when he replaced the compressor two years ago. I wonder if perhaps the Four Seasons brand compressor installed several years ago , weighing 50 per cent lighter than older, traditional brands, might be weaker. On the other hand, when I had a different shop replace the previous compressor which failed back in 2008 with an ‘old fashioned standard model’, the technician at the time told me the engine must be running at or about 2000 RPM for maximum cooling efficiency. As it is, R134A does not cool as well as R12, and I have to accept that as a given. I have the factory service manual, and in the 'heating and air ‘conditioning’ chapter (printed back in the days of R12), specific instructions are given, during the final testing of the system, after all components are checked and certified to be in order, to place a large fan in front of the car set to maximum speed to 'simulate driving conditions over 30 miles per hour." So, for now, I’ll assume things are ‘as good as it gets’. Anyhow, after spending close to three hours in the shop’s comfortable air conditioned waiting room, the owner presented me with a bill for just two hours of labor, more than reasonable, in my opinion. I was elated. If, in fact, the compressor had failed and lost all if its refrigerant, the repair could have been a very expensive proposition. Coincidentally, the shop is located just five blocks from my favorite bakery in the city, where I stopped on my way home to celebrate my good fortune.

I can. That means inadequate airflow through the condenser because the fan isn’t moving enough air.

So can we assume this is ‘normal’ then?

It’s not normal. Your fans aren’t moving enough air.

How can that be? Fan itself was replaced eight or nine years ago and fan clutch seems to be in order.

There is really no sign that your fan is not working, Mel…

Being engine driven and with nominal idle rpms in gear with AC ‘on’ in the 500 - 600 range(?); the fan is nowhere near ‘simulating 30 mph’ it’s not moving enough air, as Kirbert implies. Cooling is likely ‘as good as it is gets’ with R134A as you say.

Your very competent shop mentioned low side pressure ‘low’ at low rpms, but did not comment on high side - which implies compressor working OK? Lack of adequate condenser cooling may be involved - but expansion valve function may also be involved…?

xj6 85 Sov Europe (UK/NZ)

The only way to address this problem is by changing the auxiliary fan with a stronger one that will give you more airflow. The standard fan is week by nature, even if new.

I asked him if there might be any issues with the expansion valve, and he answered the expansion valve is functioning as it should. As far as the condenser is concerned, several months ago, I sprayed the radiator and condenser with a product used by HVAC service technicians to remove dirt, insects, and other obstructions from the fins, carefully rinsing off with clean water afterwards. This procedure did improve cooling somewhat. So, for now, during warm weather, I’ll try to restrict driving time with this car from circumstances which do not involve being stuck in heavy slow traffic conditions… I may call one of the 'usual suppliers and ask them if they sell a higher output fan which would fit in the space of the current factory supplied fan. Thank you Frank and Aristedes for your replies.

Mel R.

I spoke to the shop owner earlier today. He said high pressure readings were in order, also said if the fan in front of the condenser was not working properly we would have encountered improper high pressure readings. He confirmed to me once again that level of R134A in the system was correct, then assuring me he was not looking to sell me anything, suggested the 'modern lightweight Four Seasons compressor, though sold to me as a ‘direct replacement’ for older compressor models, simply was not designed to adequately handle the demands of the series 3 a/c requirements. Or, he remarked, perhaps this compressor is ‘on its way out’, though he found it hard to believe a two year old compressor with only 3000 miles should fail. He did remind me that when he installed this unit two years ago, he told me at that time that in the case of a series 3 system converted to 134A, the air would get reasonably cold when the car is driven at sustained speeds over 40 miles per hour, so, barring any other suggestions, I’ll live with it ‘as is’ for the time being. Thanks again.

Mel R.

Shop gives sage advice, Mel - if you can live with it ‘as is’; wait, assess and consider.

I don’t really think a new compressor will improve matters much - but do you actually have an auxiliary fan? You do not mention rising engine temps idling in traffic - which is sort of more of a concern than driver comfort…:slight_smile:

xj6 85 Sov Europe (UK/NZ)


Did you change the expansion valve when you did the R134A conversion?
If not, the system looses some of it’s performance.

As mentioned before, a stronger Aux fan will help a lot on the cooling capacity of the A/C at idle.

Yes Frank, the auxiliary fan comes on immediately when I turn on the a/c and the temperature gauge stays close to 90. I will take your advice and live with it as for awhile.

While living with it, Mel - it may be useful to assess performance against ‘normal’ behavior?

The compressor is engaged, and in full evaporator cooling, at all times with the function control out of ‘off’ - unless the compressor is disengaged by the Ranco thermostat detecting +2C or lower in the evaporator. All air first goes through the evaporator for cooling, then is deflected by the heater core flaps through or past the heater core for tempering. In cooling; the system runs flaps in full cold, bypassing the heater until set, by the temp control, cabin temp is reached - the resets to ‘maintain temp’ position.

This will likely increase the vent temp - full cooling temps is not required to maintain cabin temps…

Fan speeds are an audible indication of system’s activities. I auto they run at high speed until the set temp is reached, then drop to low. To avoid constant resetting; the AC amp has an ambient temp sensor, which bias the flap settings according to outside temps. In identical conditions; the longer the fans stay at low speed the closer the system works to spec. But there is no ‘sunshine effect’ compensating for sun heating the cabin, nor for heat generated by number of passengers - so more frequent high speed events is then to be considered…

To assess system function cabin temps near the in-car sensor should be measured - feelings of heat and cold is highly subjected and not to be trusted. Ie, normal system function should not be confused with refrigeration anomalies…:slight_smile:

xj6 85 Sov Europe (UK/NZ)

I will take note of these variables and apprise you of results the next time I take the car out for a drive. Thanks