A/c?

GO_VOLS! · 06-27-2005, 12:50 PM

Since it's getting pretty hot out now, I've been running my A/C a bit more. Something I've noticed is that the A/C doesn't seem to get cold unless I'm cruising along. If I do a lot of stop and go, it doesn't seem like it gets very cold at all. When I got out of the truck the other day when the A/C was on, I heard that little electric radiator fan screaming. When I turned off the A/C, it turned off the fan. Does that thing always run that fast?

Also, I don't know if this is related or not, but every now and then I'll get a good wif of antifreeze around the truck while it's running. When I smell this, I promptly check the engine temp and all is well.

rjspitz · 06-27-2005, 01:18 PM

Quote:

Originally Posted by GO_VOLS!

Also, I don't know if this is related or not, but every now and then I'll get a good wif of antifreeze around the truck while it's running. When I smell this, I promptly check the engine temp and all is well.

I get the antifreeze smell too when it's super hot out. Others have reported leaking hoses to the radiator, but I've looked over and over and can't find one. I'll just live with it until the radiator blows, and keep some distilled water in the truck.

TOK · 06-27-2005, 01:27 PM

Having to spin the compressor faster to get cool is a sign of low refrigerant. Have the dealer check to make sure your A/C is full. Now that its full-on hot in PA (we just had a weekend in the 90's) it takes just a bit for my truck to cool down. Once that happens, the air is very cold, and still blows cold at idle.

Bayou Titan · 06-27-2005, 02:03 PM

The Titan, as well as a lot of other vehicles, doesn't do a good job of cooling if it is not moving. I found this out last summer while I was parked at Sonic with the engine running while I was eating lunch for about 15 minutes. I was warm but when I started to drive and air got circulating over the coils, it cooled down in a hurry.

Are you parked when you have this problem? If you are try to see if you have the same problem when in motion.

Vector · 06-27-2005, 02:32 PM

R-134A systems are not as efficient as the old R-12 systems were. They are typically capable of pulling down a A/C system at idle 15 to 20 degrees (cabin temperature) colder than outside air (ambient temp). Orifice tube systems are less efficient because they are set up to work best at Idle, 25mph or 55mph. They are tuned for to work best at only one of the three areas previously mentioned based on the car/truck. GM uses Orifice tubes more than anyone, and Dodge only uses them in the Ram, PL, and PT. Ford still uses them all over the place.

The Nissan has a TXV system, this is the best of both worlds, as it has a pintle for a regulator that is controlled by a gas diaphragm. The Diaphragm sense superheat across the evaporator core and then regulates the pintle to allow more or less refrigerant to enter the evaporator. Orifice tubes cannot regulate system superheat and you have either a wet or dry evap at 75% of its operating parameters (meaning its inefficient)

The TXV will pick the most efficient metering setting for the outside air temperatures. Unfortunately the Condenser on the Titan is a little small for the Crew Cab application and the Green House that all of the glass provides creates a system problem, The sun roof shade open only makes matters worse.

You hear the blower motor screaming like mad on 90+ degree-days because the condenser size is too small for the application and the fan is doing its best to wick heat away from the Condenser. The fan is only large enough to hit about 40% of the condenser surface area. Once you start to move you effectively have a much larger fan (forced air) moving through 100% of the condenser, this is when you feel the volumetric efficiency of the condenser take place and the system temperature drops (more sub cooling is taking place).

The A/C System has several limiting factors that can affect this, Compressor size, Condenser size, Metering device type (orifice tube or Thermal Expansion Valve) and the Evaporator size. Two other items that can contribute are the Fan size on the condenser and the blower size on the evaporator.

Unfortunately we suffer from undersized condenser issues with the Titan at idle. The Crew Cab is worse than the King Cab. Most likely your system is functioning normally. Nissan picked the best system for the application, but most likely it was sized for the King Cab application and not the Crew Cab.

PuvMan · 06-27-2005, 02:46 PM

Well, i'm glad to know i'm not the only one!

Voodoo · 06-27-2005, 04:37 PM

i think its just plain dumb luck, as my a/c gets COLD fast(under 30 secs) in 95+ heat of Louisiana daily

TOK · 06-27-2005, 05:21 PM

Quote:

Originally Posted by Voodoo

i think its just plain dumb luck, as my a/c gets COLD fast(under 30 secs) in 95+ heat of Louisiana daily

Which is also why I thought the original poster had another issue. My air blows cold at idle after the system has been on long enough to initally cool the truck. Crew cab here, too.

vw1972bugs · 06-27-2005, 06:51 PM

Quote:

Originally Posted by TOK

Which is also why I thought the original poster had another issue. My air blows cold at idle after the system has been on long enough to initally cool the truck. Crew cab here, too.

I have the same results, ya got to get going for a little bit before it gets really cold.

My 2 door F-350 on the other hand...that thing CRANKS ICE COLD air at all times no matter what. Its actually funny in a way, its overkill.

eagletitan · 06-27-2005, 06:54 PM

I wouldn't know since I haven't seen my Titan since Thursday

vw1972bugs · 06-27-2005, 08:55 PM

Quote:

Originally Posted by eagletitan

I wouldn't know since I haven't seen my Titan since Thursday

Still man? Whats up with that? When will the men in blue do their jobs and get your ride back? (you dont want it back now anyway!)

eagletitan · 06-27-2005, 09:04 PM

i just updated the post today

RockyMtnTitan · 06-27-2005, 10:14 PM

Quote:

Originally Posted by Vector

R-134A systems are not as efficient as the old R-12 systems were. They are typically capable of pulling down a A/C system at idle 15 to 20 degrees (cabin temperature) colder than outside air (ambient temp). Orifice tube systems are less efficient because they are set up to work best at Idle, 25mph or 55mph. They are tuned for to work best at only one of the three areas previously mentioned based on the car/truck. GM uses Orifice tubes more than anyone, and Dodge only uses them in the Ram, PL, and PT. Ford still uses them all over the place.

The Nissan has a TXV system, this is the best of both worlds, as it has a pintle for a regulator that is controlled by a gas diaphragm. The Diaphragm sense superheat across the evaporator core and then regulates the pintle to allow more or less refrigerant to enter the evaporator. Orifice tubes cannot regulate system superheat and you have either a wet or dry evap at 75% of its operating parameters (meaning its inefficient)

The TXV will pick the most efficient metering setting for the outside air temperatures. Unfortunately the Condenser on the Titan is a little small for the Crew Cab application and the Green House that all of the glass provides creates a system problem, The sun roof shade open only makes matters worse.

You hear the blower motor screaming like mad on 90+ degree-days because the condenser size is too small for the application and the fan is doing its best to wick heat away from the Condenser. The fan is only large enough to hit about 40% of the condenser surface area. Once you start to move you effectively have a much larger fan (forced air) moving through 100% of the condenser, this is when you feel the volumetric efficiency of the condenser take place and the system temperature drops (more sub cooling is taking place).

The A/C System has several limiting factors that can affect this, Compressor size, Condenser size, Metering device type (orifice tube or Thermal Expansion Valve) and the Evaporator size. Two other items that can contribute are the Fan size on the condenser and the blower size on the evaporator.

Unfortunately we suffer from undersized condenser issues with the Titan at idle. The Crew Cab is worse than the King Cab. Most likely your system is functioning normally. Nissan picked the best system for the application, but most likely it was sized for the King Cab application and not the Crew Cab.

Wow, Vector...spoken like a true Mech Engineer! That's interesting that our Titans use a TXV over the standard fixed orifice....I'll have to go tweak my superheat...lol!

I think it depends on where you live, too. There's a larger latent load on the system in hot and humid climates vs drier climates where I live. In Colo, it's been in the 90's quite a bit this year, and my a/c is keeping up with no problem in my CC, even at idle.

GO_VOLS! · 06-28-2005, 07:48 AM

Well, yesterday I drove all the way home ~40 mins on back roads. The A/C was cranked at full fan and the temp as low as she'd go. I didn't have it on Max A/C setting b/c I've never had to use that on any of my vehicles. Even during speeds of 55-70, the cabin never seemed to cool down much. The air from the vents was a mild cold. I could hold my hand in front of the vents and it wouldn't get cold enough to make me pull my hand away.

I think something else is at work here. I really appreciate your long post explaining the differences between the systems though! Always nice to know that at least 1 other person on here knows what they're talking about.

Just kidding guys!

Chemist2000 · 06-28-2005, 08:44 AM

Same problem here! I have been posting that same problem for some time but some members seem to get too aggravated because they think theirs is very cold. The coldest I get out of the vents is 43 degrees F while moving highway speeds for a long period of time. When I start at an idle, it almost can never cool itself off unless you move. Vector nailed it in that post!! Also a windshield shade and dark tinted windows helped me, but it is still way off in its design.