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Gave my AC a decent bump of freon. On LO and recirc the vents have just really been lacking the serious cooling ability I know Toyotas have.
Yup, about 75psi too low on the high side, about 5-10 short on the low.
Blowing 50°F out of the vents now. I don't like how the manual basically only recommends using the sight glass to check the charge, but I guess it's not a bad gig as that's how old-school R-12 systems were essentially quick-checked.
It's nice and cold now, hopefully my cooled seats via the Etsy mod will really start showing their usefulness now that the summer is nearly over.
Gave my AC a decent bump of freon. On LO and recirc the vents have just really been lacking the serious cooling ability I know Toyotas have.
Yup, about 75psi too low on the high side, about 5-10 short on the low.
Blowing 50°F out of the vents now. I don't like how the manual basically only recommends using the sight glass to check the charge, but I guess it's not a bad gig as that's how old-school R-12 systems were essentially quick-checked.
@Mangsailor - You must have a leak because the refrigerant is in a closed-loop that should never EVER need freon to be added. An automobile's HVAC should be like a refrigerator or freezer and go for many decades without losing any refrigerant or needing a 'bump of freon'
Overcharging with refrigerant will cause high head pressure and cause the A/C's compressor to work harder by having too much liquid state refrigerant.
Your supply vent temperature should be much lower than just 50°F that you think is good now! It should be about 35°F to 40°F, maybe as high as 45°F on a really hot 100°+ day.
Last edited by bclexus; 08-27-23 at 06:06 AM.
Reason: orthography
@Mangsailor - You must have a leak because the refrigerant is in a closed-loop that should never EVER need freon to be added. An automobile's HVAC should be like a refrigerator or freezer and go for many decades without losing any refrigerant or needing a 'bump of freon'
Overcharging with refrigerant will cause high head pressure and cause the A/C's compressor to work harder by having too much liquid state refrigerant.
Thanks for explaining that for everyone else out there. That's why part of my maintenance program for my cars is to check the freon pressures every spring and track if I have to add freon if I ever have to do it. I appreciate your concern though.
Originally Posted by bclexus
Your supply vent temperature should be much lower than just 50°F that you think is good now! It should be about 35°F to 40°F, maybe as high as 45°F on a really hot 100°+ day.
It was 98° in the shade when I checked it, so 50° out of the vents is on-par with that chart you posted. Your last statement contradicts the chart you posted so what should I consider? The chart, your statement, or my own expertise in this?
Thanks for explaining that for everyone else out there. That's why part of my maintenance program for my cars is to check the freon pressures every spring and track if I have to add freon if I ever have to do it. I appreciate your concern though.
It was 98° in the shade when I checked it, so 50° out of the vents is on-par with that chart you posted. Your last statement contradicts the chart you posted so what should I consider? The chart, your statement, or my own expertise in this?
Your supply vent temperature should be much lower than just 50°F that you think is good now! It should be about 35°F to 40°F, maybe as high as 45°F on a really hot 100°+ day.
You said I contradicted myself in my last statement. I don't see any contradiction in my statement quoted above!
What you should consider is the proof I am providing you below, using my car's A/C as the perfect example to support my view.
My car and the garage was 98° at 5:46 pm as shown below displayed on the instrument cluster clock and I just started the car up, ran the temperature setpoint down and let the A/C run for a minute or two and shot the center vent's vane control lever with my digital infrared temperature gun and it was at 37.5° as shown below within three minutes at 5:49 pm as displayed on the analog dash clock.
[This post and the images below were posted a few minutes later @ 6:00 after I sent them from my phone to my PC so I could add them to this post.]
The proof can't be any more clear than this...
Last edited by bclexus; 08-28-23 at 05:12 AM.
Reason: orthography
This is going to be very interesting. Unlike some I'm going to say out of it, even though I see something some don't. I'm going to try and keep my mouth shut on this one.... For a minute anyway.
You seem to have a problem with my statement in which I said; Your supply vent temperature should be much lower than just 50°F that you think is good now! It should be about 35°F to 40°F, maybe as high as 45°F on a really hot 100°+ day. My statement is on-the-money and coincides perfectly with the chart below.
My car's A/C air temperature 'about 35°F to 40°F' at center vent!
@Mangsailor - It's clear that your cognitive dissonance is appalling at times!
You seem to have a problem with my statement in which I said; Your supply vent temperature should be much lower than just 50°F that you think is good now! It should be about 35°F to 40°F, maybe as high as 45°F on a really hot 100°+ day. My statement is on-the-money and coincides perfectly with the chart below.
My car's A/C air temperature 'about 35°F to 40°F' at center vent!
@Mangsailor - It's clear that your cognitive dissonance is appalling at times!
I'll bite.
The chart clearly states an acceptable range between 43* and 55* at center air vent for an ambient temperature of 100*. 50* at the center air vent with a 98* ambient temperature is well within that range, even if that performance does not match your own vehicle.
You contradict the chart by stating that 45* at center air vent is the upper limit at 100* ambient temperature.
I share @Mangsailor 's confusion. Do we follow the chart's upper limit of 55* at 100* ambient or your stated upper limit of 45* at 100* ambient?
Last edited by GrandSedanFan; 08-28-23 at 06:49 AM.
The chart clearly states an acceptable range between 43* and 55* at center air vent for an ambient temperature of 100*. 50* is well within that range, even if that performance does not match your own vehicle.
You contradict the chart by stating that 45* at center air vent is the upper limit at 100* ambient temperature.
I share @Mangsailor 's confusion. Do we follow the chart's upper limit of 55* or your stated upper limit of 45*?
It shouldn't be confusing to you at all. He said; 'Blowing 50°F out of the vents now'.
So, what does the chart show for 100° - actually 98°? The answer is: 43° to 55°. He should be seeing low 40s at most.
That is why I said; Your supply vent temperature should be much lower than just 50°F that you think is good now! It should be about 35°F to 40°F, maybe as high as 45°F on a really hot 100°+ day. My statement is on-the-money and coincides perfectly with the chart. There shouldn't be any confusion about that!
Why was there a need to add any refrigerant? It's a closed-loop system. When was the last time you ever heard of a refrigerator/freezer needing refrigerant to be added? Never! Same for modern automobiles!
So, what does the chart show for 100° - actually 98°? The answer is: 43° to 55°. He should be seeing low 40s at most.
I am just confused as to why the chart says 55* at center vent is acceptable performance at 100* ambient, but you say it is not.
Why does 55*="low 40* at most" per your assertion?
If max acceptable center vent temperature for 100* was 45*, wouldn't the chart say 43*-45*, not 43*-55*? That would be like saying "your door jamb states your front tire pressure should be 35psi cold, so you should fill it to no more than 33psi cold".
That is the source of my, and I assume, @Mangsailor 's confusion.
I have no dispute that A/C is a closed system and should not need refilling, but that's not the point here.
Last edited by GrandSedanFan; 08-28-23 at 08:17 AM.
Just a small collection of some various vehicle A/C vent temperature readings - all displaying well below 50° - in acknowledged unknown ambient conditions - to make my point...
Measure at least 3 inches into the center dash vent. Temperature should be 40 to 42 degrees F. Higher fan speeds, resulting in high air volume will result in higher vent temperatures.
The system is limited on low side temperature by a thermistor switch that turns the system off at 34 degrees F. This is located in the evaporator. Given less than perfect heat transfer to the air about 40 degrees F at the center vents is the best it gets.
@panyo64 - Are you still confused by my statement to @Mangsailor in which I said; 'Your supply vent temperature should be much lower than just 50°F'?
Here're mine again - do you see any temperature similarities to the temperatures displayed on those gauges above?
My car's A/C air vent temperature is 'about 35°F to 40°F' at center vent!
You shouldn't be confused now that I've presented my position on the topic!
Done!
Last edited by bclexus; 08-28-23 at 10:15 AM.
Reason: orthography
Just a collection of some various vehicle A/C vent temperature readings - all displaying well below 50° - in acknowledged unknown ambient conditions...
Measure at least 3 inches into the center dash vent. Temperature should be 40 to 42 degrees F. Higher fan speeds, resulting in high air volume will result in higher vent temperatures.
The system is limited on low side temperature by a thermistor switch that turns the system off at 34 degrees F. This is located in the evaporator. Given less than perfect heat transfer to the air about 40 degrees F at the center vents is the best it gets.
@panyo64 - Are you still confused by my statement to @Mangsailor in which I said; 'Your supply vent temperature should be much lower than just 50°F'?
That's totally up to you to decide. It's not my chart. I think that chart is just meant to be a general range of acceptable results for most people that may be curious and want to learn a little bit about what they should expect from their vehicle's A/C. I don't think that chart was ever meant to be taken as the gospel like you seemed to think. Remember, you wanted to join in the discussion and interject your views. I'm glad you did! It gave me an opportunity to provide additional insight and information that may be helpful to others. As you've seen now - I think you'll agree that chart is certainly not to be taken literally - at least that is the way I take it - in my view and general, generic experience.
Actually, I find the more interesting topic to be that which prompted this A/C center vent temperature discussion we're having - - that being the related topic of why refrigerant needed to be added to a late model Lexus A/C system!
Car owners nowadays are going many, many decades and never needing to add refrigerant like they used to have to do many generations ago. Vehicle A/C systems are much like refrigerator/freezers and rarely, if ever, leak refrigerant requiring a 'bump of freon' as @Mangsailor called it. It's practically unheard of nowadays.
My question for @Mangsailor is - What was the circumstance or condition that actually caused you to think your car's A/C system might need refrigerant to be added?
Last edited by bclexus; 08-28-23 at 01:17 PM.
Reason: orthography
On the 1st post - (Post #5365), about the charging I had the same question? Why was it low?
Also the post stated he was checking always.... in the Spring? Was it checked in the Spring and now checked again? It's Aug and was it was low, from Spring to now Aug? Was any work done that had the a/c lines or system disconnected to do, then on putting back together the level never was correct?
Post #5365 statement was - "That's why part of my maintenance program for my cars is to check the freon pressures every spring and track if I have to add freon if I ever have to do it."
Knowing what I know about a/c's and Freon, experience would have me doing a Dye leak test with a U/V light in this case.
*For the record I am not trying to start, just saying - check for a leak is when and how, in a low Freon situation, as low as that amount was missing.
08-26-23, 01:37 PM
Adding some Freon discussion
Higher fan speeds, resulting in high air volume will result in higher vent temperatures. 
