2005 s type, my ac is only blowing cool so I too in for service...the vacummed it refilled no leaks...still just blows cool.

The compressor keeps disengaging too soon on both low and high side.

The high doesnt get above 200 and the low doesnt go below 40. It just cycles too soon to cool car down.

Are there low or high pressure switches on these? Where is the switches?

Thanks

 

Anyone else have this problem?

 

Your compressor may be failing. Not unusual in these cars. Your symptoms sound similar to my car in May/June 2010 as my factory compressor slowly faded away. Quite a few of us 2005 S-Type owners have had to replace our compressors as the years have rolled by. Keep in mind that aftermarket compressors are less costly and may be better quality....

 

The Pressure Cut Off Switch (item 3) could be the cause.


(click on the image to enlarge it)

The Pressure Cut Off Switch monitors the A/C compressor discharge pressure. The ECM interrupts A/C compressor operation if the Pressure Cut Off switch indicates high system discharge pressures. It is also used to sense no or low charge conditions. If the pressure is below a predetermined value for a given ambient temperature, the ECM will not allow the clutch to engage.

There is also an A/C compressor pressure relief valve in the compressor A/C manifold.

Graham

 

Can you please clarify something? When you said "the compressor keeps disengaging too soon", are you saying the clutch is physically releasing? I think that is what you mean, but I want to be sure.

Or does the clutch stay engaged the whole time? This detail determines the next step in troubleshooting.

If the clutch is disengaging, we are probably dealing with an erroneous signal (from a bad sensor, for example) commanding the clutch to release.

If the clutch stays engaged the whole time, a worn compressor or slipping clutch is the likely culprit.

Also, can you confirm the shop added the correct amount of refrigerant? Does the invoice mention how much was added? I'm a little rusty at interpreting gauge readings, but your symptoms could point to low refrigerant. If the correct amount was added, and barring a major leak, we can probably safely rule out that possibility for the time being.

 

I thought adding refrigerant needs the compressor operating to pull it in....

 

Another suggestion I should have mentioned earlier:

On the control panel, use the temp select up/down button to drive the commanded temperature all the way down. The display should say LO. This bypasses some portions of the climate control system and helps determine if a faulty temp sensor or other component was at play. In other words, the basic AC system is fine and is putting out proper cold air, but heat is being inadvertently added downstream by the rest of the climate control system.

Another thing you can try is to let the engine cool off completely for several hours, preferably overnight so the cabin isn't already hot. Then take an AC duct temp reading before the engine warms up. You've got maybe 4 or 5 minutes before the coolant warms up again. If the duct temp starts out cold and slowly warms up, that's further indication the AC portion is fine but heat is being added downstream. A good example would be at least one side of the DCCV not closing fully and letting the heater core dump heat into the cabin when not commanded.

Also, I've been reading up lately on the climate control system and can bore you to tears, if you'd like. Maybe I'll come to be known as the Cliff Claven of Climate Control (4C™), full of alleged "knowledge" but little useful information. My apologies to non-US readers, you'll have to look him up to understand that one...

You had asked about high and low pressure switches, but technically there are none. The low side has no pressure switch of any kind. (Low system pressure is determined indirectly by reading the evaporator discharge temp sensor in the cabin.) The high side has a pressure transducer (referenced as the Pressure Cut Off Switch is post #4 above) but this isn't a conventional on-off switch like you might think. It's a pressure transducer that's feeds the PCM with a variable electrical signal proportional to the high side pressure.

Personally, I think it's very confusing that Jaguar calls this a cut-out switch when it isn't an on-off switch per se. I'll call it a transducer to keep you confused, but do be aware of Jaguar's different nomenclature. Oh, anyway, if you had a certain failure of this transducer/switch thingy (see, even I can't make up my mind what to call it...), that could give you the symptoms you've reported.

Before you start changing any parts, though, please let us know more details. Specifically, please see my earlier question asking if the compressor clutch is actually releasing or not. And set the control panel to LO and also take an AC duct temp reading while the engine coolant is still cold.

 

The clutch kicks in just runs for a few seconds then kicks out...the result is inside the car the it blow cool but not cold because the compressor isnt running long enough....the tech said it could be a high or low pressure sensor since neither is hitting the range they should before the clutch kicks out....I watched him put the freon in he vacuumed it down for 30 mins did a 5 min leak test the filled it up like 1lbs 10 or 11 ozs....

 

Thanks for the update. The details of the clutch operation will help with troubleshooting. Did you ever try setting the controls to LO? That will help rule out some other factors.

One of my first thoughts is low refrigerant, but 1lb, 12oz is the correct amount, so hopefully that's not the issue. What was the AC doing before you brought it in for service?

Now please understand I'm always hesitant to suggest, "Change X component" and then have you report it made no difference. So please remember how much I'm charging for my advice ($0.00) and adjust your expectations accordingly. Others will more experience may suggest certain courses of action, but as an honorary Scotsman, if presented with two likely options and one is significantly cheaper than the other, I'll try cheap first. I may cause you more work but hopefully not break your wallet in the process, but just be aware my skinflint troubleshooting tactics are not for everybody.

At the moment, and my thoughts tend to change with the shifting wind, I'm leaning towards a bad evaporator discharge temp sensor. From my earlier message, this is the defacto control for the low pressure side of the system. This temp sensor infers the pressure on the low side of the AC system, and helps control the clutch operation.

I don't have the Jag part number, but it's actually supplied by Ford and is YH1504. This sensor is available from many sources, including your local Ford dealer, auto parts stores, multiple online sources, etc. This sensor is used on many Ford vehicles. You should be able to find one easily in the $20 price range.

This same sensor is used in three places on the S-Type. The first is the evaporator discharge temp sensor, as mentioned above. The other two are in the ducts that distribute conditioned air to the driver and passenger sides of the cabin, as controlled by the two temperature settings on the control panel.

I mention these other two so you don't get confused while searching for them under the dash. Access stinks, no two ways about it. You have to lay on your back in the left footwell to reach this one. This one is on the side of the center area, slightly above and inboard of the gas pedal (LHD models) if I remember correctly. The other two sensors are more outboard, one on either side under the dash. In case I've confused you, one duct sensor is on the right side of the dash, but you don't need that one. On the left, you'll find one duct sensor outboard (don't need that one), and the evaporator sensor you want is inboard. Here's the sensor, so you know what to look for:




Motorcraft YH1504 Temp Sensor


The long finger-like probe sticks into the evaporator housing. The only portion you'll see exposed is the rectangular portion for the electrical connector. The sensor just snaps into a hole in the evaporator housing. You'll have to wiggle the sensor and pry it straight out for removal. It's best to undo the electrical connector first, because once the sensor is loose, there's not enough room for two hands to undo the connector.

Now, if you really want to be cheap, you can swap with one of the duct sensors and see if that makes any difference, assuming they are good. Even as cheap as I am, with access being so miserable, I'd personally spend the $20 for a new sensor in the evaporator position and hopefully never have to crawl under there again.

If that doesn't get it, the poorly-named Pressure Cut-Out Switch as mentioned in post #4 is your next likely culprit. I think access is only fair under the hood, but it has a self-sealing valve so you don't have to evacuate and recharge the refrigerant.

Hopefully some others will chime in, so you're not spending time and money based solely on my ever-changing thoughts.

 

Thank you so much, I order sensor now...I did try the Lo settings no change...Ill keep you updated.

 

Kr98664, thank you so much I replace that sensor today and bam cold air is a blowing hard......I really appreciate you taking the time to help.

 

Groovy! Glad to hear the good news. Wasn't quite sure what to suggest next if that sensor or the pressure cut-out switch didn't fix it. Thanks for letting us know. Of course, now my head is swelling up way too much and I'm having trouble reechin the kevboord to tipe...