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Hey guys! Second post. Only because I posted in the wrong section lol. I just bought a beautiful 91 XJ40 (Just learned the difference lol). The AC was not working or blowing. When I checked under the hood, I notice that the Compressor drive belt and the air pump drive belt was not on at all. So I put a belt on the compressor (still waiting on the air pump drive belt to come in, but to my knowledge, that is for emissions) and no ac. I checked the fuses in the front for the blowers and no blown blower fuses. I also learned that the blowers need vacuum in order to open the vent for the blowers. I pulled the hose (See picture) where the vacuum is suppose to be and no vacuum. Could that be the problem? I find it very strange that both are not functional at all since they are independent of eachother.
Welcome to the Jaguar Forums! It's great to have you with us!
A common reason the A/C compressor belt is removed is because the compressor is making noise, so once you recharge the refrigerant, don't be surpised if your compressor is noisy.
Off the top of my head, those vacuum solenoids operate the recirculation flaps. Their default position closes off the duct to the passenger compartment and opens the duct to the fresh air inlet under the windshield cowl. When vacuum is applied, the flaps, which are hinged along their top edge, tilt toward the firewall to seal the fresh air inlet and open the duct to recirculate air from the passenger compartment. You will probably only have vacuum on those lines when recirculation is selected on the control panel. But you should also have air from your dash fascia vents regardless of the position of the recirculation flaps.
The most common causes of inoperative blower fans is failure of a relay or the speed control circuits inside the blower motor housings, or the microswitch in the control panel. For some helpful diagnostic and repair information, see the Jag-Lovers XJ40 eBook:
The system is designed with two blower motors, one at each end of the dash. The fans blow toward the center of the dash, and their opposing airstreams are supposed to cause sufficient airflow from the vents with minimal noise. If one blower motor ceases to operate, the remaining fan cannot generate sufficient airflow. If you hear a fan running but have little airflow, you may be able to detect which fan is inoperative by listening closely. A method of definitive diagnosis is to remove the fuse for each blower motor one at a time, and when you hear a fan cease to operate when you pull its fuse, that is the one that is still working - the other one is inoperative. It is not uncommon for an owner to drive an XJ40 with only one operative blower motor and for the remaining motor to eventually fail, so that both are inoperative.
I am attaching a few other documents that may be helpful. I also have a Dealer Training manual for the Delanair IV system but it is too large to attach to a post so send me a private message with your email address and I'll email it to you.
Hi - I'm guessing that the blowers aren't running, i.e. blowing air, either hot or cold?
Sometimes the speed control circuitry fails and they only run at high speed, so turn them up full to check. I don't think you'd get much happening if they aren't running and even though they are powered individually, they are controlled (together) by the climate control panel switch.
If cold (a/c) is selected and the climate control panel is working (it can fail too, check forum for micro switch issues), the compressor clutch should engage independent of whether the blowers are working or not. This pre-supposes that the a/c system is also in working condition and not low on charge etc.
BTW, has the system been converted to R134A or does it still have the original R12? There should be a label somewhere under the hood telling you what you have in there and how much.
We've all had to fix our climate control systems in one way or another so there's plenty of experience here with the idiosyncrasies of the different year cars.
Best to put the last six numbers of your car's VIN in your signature file so we can give you the correct advice for your model. Although there are some similarities, my 94 is quite a bit different to your car.
Hi - I'm guessing that the blowers aren't running, i.e. blowing air, either hot or cold?
Sometimes the speed control circuitry fails and they only run at high speed, so turn them up full to check. I don't think you'd get much happening if they aren't running and even though they are powered individually, they are controlled (together) by the climate control panel switch.
If cold (a/c) is selected and the climate control panel is working (it can fail too, check forum for micro switch issues), the compressor clutch should engage independent of whether the blowers are working or not. This pre-supposes that the a/c system is also in working condition and not low on charge etc.
BTW, has the system been converted to R134A or does it still have the original R12? There should be a label somewhere under the hood telling you what you have in there and how much.
We've all had to fix our climate control systems in one way or another so there's plenty of experience here with the idiosyncrasies of the different year cars.
Best to put the last six numbers of your car's VIN in your signature file so we can give you the correct advice for your model. Although there are some similarities, my 94 is quite a bit different to your car.
Welcome aboard,
Larry
Thank you for such a detailed post. Ill answer your questions in the order you asked them.
Sometimes the speed control circuitry fails and they only run at high speed, so turn them up full to check. I don't think you'd get much happening if they aren't running and even though they are powered individually, they are controlled (together) by the climate control panel switch.
Should I replace the climate control panel switch first?
When I turn the air from "off" to "low" it makes a sound from underneath center console area. It sounds like a mixture of a puff of air and a solenoid lol. I don't know if that helps at all.
I believe its the R12. I bought this car from the original owner who said everything is stock and mostly garaged.
Thank you for the tip. I will add that to my signature! My vin is: 632761.
Should I replace the climate control panel switch first?
Only if the panel is dead, i.e. no lights or any noticeable change in anything to do with the climate control.
When I turn the air from "off" to "low" it makes a sound from underneath center console area. It sounds like a mixture of a puff of air and a solenoid lol. I don't know if that helps at all.
So the blowers aren't blowing at all, just an initial pfft, then nothing?
I believe its the R12. I bought this car from the original owner who said everything is stock and mostly garaged.
Ok. Most systems got converted to R134A but R12 is still an option in the States and can still be bought, I think it might be expensive though?
Nick runs R12. He's the expert on a/c too - he taught me a/c theory right here on this forum!
So - things to sort out before delving into the a/c.
Are the blowers running at ANY speed? If so, are both running or just one? Is the panel completely dead?
Once you get the blowers operating, we can look at the other issues (if there are any!)
Hey Larry! The blowers are not running at any speed. I actually think the panel may be completely dead. None of the lights illuminate on that panel, but do on the panels beneath them. But like I said, when I turn it from "off" to "low", it does make a sound as if it activated a solenoid. And I do have a few more issues, but your right, we will solve them after this one lol
I believe its the R12. I bought this car from the original owner who said everything is stock and mostly garaged.
The vast majority of cars were converted. Most are simple and straightforward to convert, including the XJ40, so it wouldn't have been a major modification. You can tell by, as Lawrence stated, a label somewhere in the engine bay (often on the inner fender in front of the battery). Also the service fittings give the conversion away. Retrofitted cars will have a quick-connect style conversion adapter screwed onto the R12 fitting, often with red Loctite on the threads.
The conversion wouldn't affect the original functioning of your climate control system, heater or ventilation, so that issue needs to be ironed out first.
I'm a little concerned about the missing belt. I absolutely agree with Don: Belts are typically removed as a free/cheap solution to avoid replacing failed parts or to prevent an impending failure. A/C compressors aren't the most reliable, especially older units like ours, and failed bearings, clutches, or even catastrophic internal failure aren't uncommon.
If the system has been converted to R134a, we can connect a relatively inexpensive can of refrigerant to the low-side service port, allow a charge into the system, and jumper the compressor clutch relay for a second or two to see if the compressor and clutch are even operable. Most chain auto parts stores will have a tool rental program for a small deposit. You can rent a proper set of manifold gauges and a vacuum pump to properly diagnose and service the system. They can also be purchased from discount tool suppliers like Harbor Freight for roughly $150 for both. Mine have paid for themselves many, many times over.
If your car still has an R12 system, things get a little trickier. I took the EPA Clean Air Section 609 certification test in order to be able to legally buy small amounts of R12 and service the system in my car. If you're not willing to do this, you'd need to find a properly equipped facility to do the work for you which is very, very expensive. Most owners have decided that R134a conversion is the easier and cheaper way to go, without sacrificing too much in the way of comfort, especially in favorable climates. Some don't notice any impact to performance at all.
The conversion process to R134a involves recovering any refrigerant if present, breaking open the system, removing the old dryer bottle and replacing it with one that contains desiccant (to absorb any moisture in the system) that's compatible with R134a, removing the compressor to drain the old mineral oil out and replace with Ester oil. Ester oil is compatible with both R12 and R134a, as well as any traces of mineral oil. Mineral oil does not mix with R134a and any remnants will find a low spot in a converted system.
GM, in their R134a conversion research back in the 90s, found that up to an entire full system charge of mineral oil (their cars often used 8+ ounces of oil! Our cars use about 4.5 ounces...) could be left in a converted system without any adverse affect to longevity or performance. They had a lot more money for R&D than Jaguar, so I'm inclined to trust their research. Because removing the compressor on an XJ40 is such a bear of a job, it's a huge time savings.
Jaguar also specifies replacing the compressor front seal with one of R134a compatible material. This is not often done in the field, unless the dealer is performing the conversion. I additionally recommend replacing the expansion valve while the system is open; they are very cheap. Service valves are fitted, and a retrofit label is affixed in a prominent location. The system is evacuated for some time (I do it as long as I can, sometimes overnight) to boil off any moisture in the system before charging. You can find leaks when pulling a vacuum on the system by closing the manifold valves, and checking to see if the vacuum level drops over time. And then it's on to charging the system with the proper amount of R134a.
08-04-2019, 06:20 PM
I need help with A/C!
