A/C troubleshooting

Ho much R134a did you put in the system? That could be your issue although 48 degrees out the vent (if it is summertime) is pretty good.

 

I put in 24oz. Probably a little less since some coolant gets trapped in the lines of the manifold gauges. According to Google my temps for an 81 degree day with 83% humidity was in the range of normal. I decided im just gonna live with it for now. I want to test the temps again on a 75 degree day with no humidity and see where i am at.

 

My 99 taco AC label under the hood says 1.21 lbs (19.36 oz) is the min fill 1.65 lbs (22.88) is the max fill, - check what yours says. If it's the same, you have a bit too much in the system. I put in a bit under two 12 oz cans, and my system blows cold. If your tag reads the same as mine, I'd release a bit out. I know that sounds counterintuitive, but too much freon makes your system less effective.

 

Thats interesting. I will look at my label. When I was adding it, i had a thermometer hooked up to the central vent and connected to my phone via bluetooth. It was coldest when I added both cans fully. I assumed it might need a bit more. The guide I used (from tacomaworld) said to put both cans fully in the system.

My suspicion is that there is still too much oil in the system. I originally did this about 2 weeks ago but the temps were in the low 60s, so I took it apart and redid it by adding only 100cc's to the compressor instead of 125cc's like the guides stated... The Denso compressor claims that it has all the oil it needs to run properly. When I measured the oil by draining it, it came out to about 75 cc's. The documentation from Denso says it should have about 100cc's. Toyota claims the compressor needs 125cc's. It's crazy to me that you need 125cc's of oil for the compressor, 40cc's for the evap, 40cc's for the condenser, and 20 cc's for the dryer. That is ~7oz of oil flowing through the system. Seems like way too much. I don't understand why any of the parts other than the compressor need oil. Maybe somebody who is more educated on this than me can explain why I need so much oil, when the compressor only calls for 100cc's.

The first time i recharged my truck 3 years ago before i fixed the leak, i added 2 cans and the system was blowing in the upper 30s... I am kinda annoyed with all this. 2 full replacements of the system in 2 weeks, has me blowing through the process pretty quick, but I annoyed at the results.

 

Ok, I am beyond frustrated. Here's what ive done so far;

1. Replaced the Compressor, Condensor, Evaporator, AC/Dryer, expansion valve, pressure sensor (all Denso/OEM), all seals, flushed and cleaned lines (drained and filled each component with specified oil cc's)
2. Pulled a vacuum on the system (it held for 12 hours)
   
3. Charged with 24 ounces of r134a while at 2000 rpms
   
4. Checked my blend door actuator, its working fine (makes some weird clicking sounds when cold starting, but it moves the arm from cold to warm just fine)
   
5. Checked my pressures. They are a little low, but are in range for temps/humidity. 87 degrees 80 humidity had low pressure at 38 and high at 215.
6. Check my control unit for bad solders (its fine)
7. Replaced my AC blower motor

I'm just at a loss my temps are 60 when idling and 48 when driving down the road at 60 mph. When I turn off the car and run into a store for 5 mins and come back out, the temps in the AC system are 70 again and then go down to 60 at idle, and only dip into the low 50s/upper 40s at high speed. What the heck is going on? Is my truck still somehow mixing heat from the engine with the cold air? Is there a way to check specifically the heater door? The low pressure line coming out of the evaporator to the engine bay is frosty/cold to the touch.

 

0. Have you verified the A/C belt is snug correctly (not loose)?

1. Did you put die in the system? If you have, have you checked for leaks with a UV light? My leak came from the backside of the dryer (bad o ring), it was hard to see until I removed the front grill.

2. The low-pressure line being cold is a good sign, you have freon in the system and the system is cycling on the compressor. Can you put an IR gun on the line to see what the temp is coming from the evaporator? Put the gun very close to the line to get the most accurate reading at the line coming from the firewall. What does it say? If it is 40 F, then there might be reason to believe some hot air is being mixed in. If it reads in upper 40's I think this may tell you its not being mixed with hot air.

3. To clear the possibility of hot air being mixed, get a clamping devise to pinch off the flow of hot water to the heater core. you might want to pinch of both hoses while the engine is cold. These are small clamps, so you could drive the vehicle and see if you notice a change. If it is still the same temp, then you know it's not hot air being mixed.

4. You do have a bit too much freon in the system. And your comment about the oil fill amount may be too much could be a factor in the less than optimal performance. If you are this far down the list, you may have to bleed the system and remove and drain the compressor and dryer of oil. If you can, measure the amount of oil removed from the system. Then, refill with new oil just in the compressor, no oil in any other item as you may have plenty of oil in the evaporator and condenser to spread around. Put a vacuum on and make sure it holds for 12 hrs with no drop. Then put in 1.75 cans (12 oz) of straight freon (freon with dye would be okay) but nothing with a leak additive or oil!

If step 4 does not fix it, you may have to take it to a shop. Write down all you have done so you can pass it on to the tech so he can focus his efforts on areas you may not have covered. I was pressed for time and used a dealer and an independent shop before I finally fixed the problem myself - it was the bad o-ring on the back side of the dryer for me. Replaced the dryer and o-rings and A vacuum and recharge returned the system to oem performance.

Keep us posted.

 

Thanks for your reply

0. yes, the belt is snug. (maybe a little too snug? I can turn the belt about 90 degrees when twisting it

1. dye was in the oil that i added to all the components

2. this sounds like a good idea. I will for sure try this

3. this also sounds like a good idea. I will also try this.

4. this will be my last resort (it will be the 3rd time doing this, im hoping it doesn't go there again.)

 

It might go to #4 again. You would be doing it a 3rd time because it will only cost you 2 cans of feon (<$40) and some time. If you pay a tech, you are in it for $500-600. It might be closer to $400 if their evac can pull the oil out too. Don't put too much freon in the system, perhaps only 1.5 cans worth initially and verify the temp of the low side coming from the firewall. Write down these figures as you go so you can verify the progress/troubleshooting.

 

So when you are charging the system, you are checking the firewall line coming from the cab with the infrared thermometer? You aren't checking the temps from the vents? I was using a bluetooth thermometer hooked up to my phone. While I charged it this time, it never got below 60ish while at 1500 rpms. I was adding it slowly and it kept getting colder even to the last bit in the second 12 ounce can.

 

You should use the vents, but since you have not eliminated the heater core mixing with cool air (blend door) the check with the line coming out of the firewall is so you can compare to your current state (once you are in step 4).

 

So just to confirm step 4, you think I should take off the compressor one more time, drain all the oil from the compressor, add the 100cc (specified by Denso for this compressor) to the compressor, vacuum it, add 1.5 cans of r134a and go from there? Should I replace the AC dryer if I am just opening the system for a few minutes to drain and refill the compressor?

 

If you have borescope I would look at the blend door and how it seals. The factory has foam to seal and to keep it quite. The foam that seals the ducts t\when they slip into each other is probably long gone as well as thge blend door seal. If it was me i wouldnt worry too much, lots of work for very little benefit.

 

Where would I stick the camera? How do I access the blend door? I know where the blend actuator is and have verified it is working, but my thoughts were it's possible that door isn't closing all the way.

 

OP, you can try the camera, but the clamps are simple and eliminate the heat question altogether by pinching the lines closes.

 

What size hose clamps do I need? I ordered the infrared thermometer a few minutes ago.

 

either should work. If you do not have a harbor freight near you, cry an auto part store, they have this kind of tool.