Let's Check the A/C! 2000 Taurus

 I can hear the clutch cycling, radiator fan running and no unusual noises. I usually set the A/C for coldest air temp and put the thermometer in the center vent. This one is definitely not reaching full potential. I'm looking for the temperature to reach 50F or better and I don't see that happening here. Roughly at 75F and I have the constant clutch cycling. 

I suspect there is a low refrigerant situation. Compressor clutch will cycle off if the pressure gets too low or too high. The scenario would be compressor clutch engages, low side pressure drops too much, clutch disengages. You can verify system problems with a set of gauges and monitoring both high and low side pressures. In this particular case though I think the best move now would be verify the system charge. Time to recover the refrigerant and see just how much is in the system. Something that I should mention is not possible with a "charge kit" from your local parts supplier. 

Initial pressures are about 75. How much refrigerant is that? You can't answer the question from system pressure. You have to recover the refrigerant and weigh it. The recovery machine does that job very well. 

We recovered 10 oz of refrigerant so roughly one-third of a full system charge was present. Set the machine to a correct charge and fill the system.

 

Now we have A/C!

With no obvious leaks we'll depend on the UV dye in the refrigerant to do its job if the charge gets low again over time. 

Thanks for reading!

Kenny@ggauto.repair

Actron U-Scan (screenshots)

 One of my favorite things about the U-Scan is that you can run the app on iPhone, iPad, Samsung tablet or Samsung phone. Shots from all. 

Thanks for looking!

Kenny@ggauto.repair

Alldata Mobile

Alldata Mobile puts the power of the Alldata Repair information system on your tablet and combines it with a wireless OBDII dongle for basic scan and code capability. There are certainly times this will save time and steps. There would be a lot to cover here but lets just post some screen shots and let me save the typing for next time. 

Thanks!

Kenny@ggauto.repair

  

Let's Check the A/C! 2001 Tahoe

Check the settings. The fan should be at the next to lowest speed. Technically low should be the coldest air but some cars have a barely noticeable flow at the lowest setting, so I tend to use the second position. Verify the fan does run and that you do have airflow at the vent. Center vents should be coldest so when necessary I put a thermometer in a center vent. I can feel by hand this is not cold but I'll put the thermometer in so you can see as well. Set the temperature control to coldest. Select recirculate or max air. This position will take longer to cool the vehicle interior but we are measuring at the vent. Once we are doing a drive later we want to see the vent temp reach at least 50 F once the interior has cooled before it gets a stamp of approval. 

Ok, 120 F seems to verify a non-functioning A/C. 

Turning the temperature control to full heat does get warmer so the temperature blend actuator is capable of moving. 

I'm not testing the heater today so I'm not going to see just how hot it will get. This seems a good time to point out that failed blend actuators is a very common cause of A/C not getting cold. 

Time to check under the hood. We want to verify the A/C compressor belt is present because these are known to lose belts. The belt is fine. The compressor clutch can be turned by hand so the compressor isn't seized. We want to know if the compressor clutch engages when the truck is running with A/C on. It does not. Now if the wiring at the compressor was more accessible I might do an electrical check there at this time but it is not. Following the path of least resistance then we will check the system charge. 

Let's call in the heavy equipment. 

Now I can't swear the blend actuator is 100% and I can't swear we don't need some refrigerant, but I do know we have enough pressure on the system that the compressor clutch should engage and it doesn't. Let's continue. I think, because I'm not yet ready to dig around the compressor harness that we should do our tests at the compressor relay, which actually appears to be disconnected and just laying in position vs pressed into the connectors. 

Apparently someone has removed the relay and did not fully engage on re-install. Now the compressor clutch is engaged. I've reached my target of 50 F at the center vent and we're done. I'm sure that no one will have any idea how that happened. 

Thanks for reading!

Kenny@ggauto.repair