04 A/C issue

[TN_4runner]

Hello everyone...I did search on my issue and was unable to find my issue..so here we go. I have 04 2wd v6 126000 miles. I have had this runner since '10 and no issues since this. First off is what I notice is that the A/C or "compressor" is working, it cools, the issue is how its cools. I hooked it up on the gauges to check Freon level, sometimes it shows correct level and sometimes it doesn't, I did 2 different set of gauges..like the ones from the auto parts store.. Freon add cans with gauge. One time both show good charge and both show issue like in over charge another time. My issue is when I turn the A/C on like in the morning, first thing going to work, nice and warm and humid outside it works fine, outside temp 79 and humid. At this time the A/C is blowing 41-42 degrees consistent, I have a A/C temp gauge in my vent to check. Ok so get off work same day 5ish nice 90-95degree temps very humid, run the A/C, it cools somewhat to about to 55-70 degree compressor running...then it jumps to about 80 degree blowing...then again back down to 55-60 degree this is going on for about 10 min after I start it up. After all that up and down temps the A/C starts working consistence till when I get home about 20-30min later...cooling a 40-41 degree. I might go out later that night, the A/C works just like it did in the morning..no issues. The following day it will act the same way just like I described. This has been going on the last week now.

Now what I notice is that the compressor isn't going through its cycles, what I mean is when it's on cooling the compressor never kicks off, constantly running cooling, it will run for minutes, at least 5 min at times without cycling off. It's not doing the cycles like every 30 seconds or so..off and on. To me it should be kicking on and off a lot. I do see lots of condensation on the low pressure line, like it sweating a lot. No frost or nothing on the line, just water dripping all over it.

I don't know if it matters but when I'm running the A/C in the morning or late evening it get colds in the cab, "not during the day obviously" I turn the temp dial up to around 70 degree or so and I look and the temp gauge that I put in the vent check will show blowing at 41-42 degrees still, never changes temps for how ever long I run the A/C. To me the A/C compressor will not shut off giving me the adjusted temp I'm trying to set, it's constantly blowing cold. Its during the day time heat is when I have issues cooling.

Sorry for the long post and I tried to explain everything I can see. Any A/C folks might know what's going on? Sensor? I read some posts on the magnetic clutch on the compressor..idk?

Any info on what to check will help...I'm not much on A/C repair :doh:

FIY... I didn't mention all my temps I'm talking about on my gauge was running the A/C on low set and on high fan in the circulation cabin setting.



Thanks

 

[toyo]

Ok, let me see if I can shed some light on this for you.

For starters the compressor won't kick off unless the multiple sensors tell it to. You have the outside temp, inside temp, solar sensor, humidity sensor, coolant temp sensor. All these dictate to a varying degree the function of the a/c system. Don't fret about the compressor not cycling unless you know for a fact that the set temp has been reached.

When you see the gauge readings move it is because the compressor is cycling. When the comp turns off the pressures will of course go up.

Some general rules to follow:
The static pressure of both the high and low side should be pretty close after the engine is at room temperature.
The high side pressure is generally 2.2 times the outside ambient temp. This is while the compressor is running.

Does the vent temp go way up if you idle for awhile? Or only when driving?

My thoughts on your problem are numerous...

1. You could have a high or low pressure switch acting up.
2. Possible bad relay malfunctioning intermittently.
3. The coil in the compressor could be going bad.

If I was diagnosing this I would check to see what the compressor is doing when it starts blowing warm. 40-41 degrees in pretty darn cold so i would not think the pressures are too far off if any. If you do not have or had a freon leak your freon should be at the factory level. Kinda like brake fluid. If you never remove any brake fluid yourself or from a leak you should never have to add any brake fluid.

BTW, when you check your temp readings Toyota says to put fan on high and in the lowest temp setting which will automatically set recirculate on. I believe they say to leave one door or window open. Let me see if I can find the page for you.

Let us know what you try and what happens!

 

[toyo]

Read this, it might help you.

 

[DC runner]

I just wanted to add to the part about compressors. Since the function of the compressor is to compress the freon, thereby creating the "cold" which is then utilized via air blow grill temp exchanger, a compressor will continue to function as long as it is required to cool the air.

Home HVAC and car ac operate under the same basic principle. While the compressor will kick on and off if the internal air temp reaches desired temp, constant compressor cycling on and off is not a test for normal function. Setting the temp to "low" and leaving it in manual mode will have the compressor kick on, begin to cycle freon, and stay on for the duration.

Something about your description of the temp variations make me wonder if the compressor is on its way out. Similar to a fan on its last legs. Turn it on and it grrrrrrrrs to high heavens. Give it 5 min, and the heat has loosened whatever there is and it quiets down. Fans can last varying lengths like this, but eventually they seize up.

I am not an HVAC expert, but are not compressor internal moving parts lubricated by oil in the gas? Perhaps yours is starting to head south? Then again.... I don't pretend to really know. I understand the thermodynamic concepts surrounding a compressed gas,forced air heat exchange climate system such as your modern car ac or central air for a house.

 

[TN_4runner]

Does the vent temp go way up if you idle for awhile? Or only when driving?


The vent temp will go up on both idle and driving. You can definitely tell from the musky smell when the compressor kicks off. I went to Batesville MS Friday afternoon which is about an hour highway drive away. It messed up with the temp change for about 30min that day, up and down when I got in to leave. It cool to 42 degree for about 3-4min and then vent temp would rise to about 75 degree in about a min, hang there for a minute and then it cool back down to 42 degrees and stay there again for about 3-4 min. It did that cycle for about the 30min. Then for the rest of the ride it stayed cool, that consistent 42 degree temp...heck I started to get cold and turned the fan down on med but kept the temp on low. It was hot that day, mid 90 with heat index of around 100. Got to Batesville parked about an hour, got back in to leave, turn A/C on and it works fine, keep in mind its early evening and outside temp has dropped. Drive home is hour and half with no issues.

The compressor makes no whinning or grinding noises, its quiet like a normal compressor.

To me it seems the hot outside temp affects the performance during the daytime only, early morning and evenings or nights are fine.

BTW...that A/C line that runs in front of the radiator, the circle clear window to look through next to the high pressure input, are you supposed to see the bubbling effect in it? I never see it mine if it matters, I watched it and nothing happened while the compressor was running..

To me it seems I have a bad switch high or low switch. I don't know about how to check or replacing either or?

Or is there a temp sensor or something that can go bad?

 

[earthrealm]

My ac has been performing poorly for sometime now, it appears it has a leak somewhere as i have had need to be adding refrigrant evry 6 to 10wks...worse if the truck is parked for a wk or 2.the techs have looked at it, and cant determine where the leak is coming from, the last tech said its from the compressor area, that i need to change the compressor...........initially was thinking it would be the common evaporator failure.

i intend to try the dye n uv light approach, to be 100% its the com pressor, b4 tossing $$$s down the drain, from my research, oem compressor gets as high as $800, while after market is abt $250....

has anyone had a leaking compressor issue b4?


note: the techie added greenish oil to the ac system and after 2wks, i brought the car back and he tried tracing the oil, none was found in the drain pipe/area, he said he found traces of the oil in the compressor bearing area, making him suspect its the compressor that is leaking.

 

[TN_4runner]

update

Since posting this last year and giving a update today I have had no issues since then, I have done nothing with or to the A/C. It's been hot and very humid for months and has not acted like it did last year, blowing a 40-42 constant degree temp since using it full time as of April. IDK :crazy:

 

[fdbyrne]

My wife has a little Ford Focus that does this same thing. The A/C works fine unless it's really, really hot outside. When it is really, really hot (like when we took it on a road trip to TX) the A/C will blow cold air for a few minutes, then hot air, then cold, then hot, etc.

I'm not an expert on HVAC issues. I don't understand why it would work fine for any external temperature up to about 95 degrees and then crap out when you need it the most. It's a simple HVAC system too. No electronic climate control that could be the cause.