Topic: auto air conditioning repair

[79coyotefrg]

its that time of year and ive seen a few threads on TTORA and been trying to find the info myself

the 95 suburban we have needs a compressor but should it be a new compressor or is a reman ok??

 do i HAVE to get the dryer (looks like a BIG coke can) or can it be flushed with rubbing alcohol and then a vacuum pump suck a vacuum on the system??
(i have access to one of these thanks to my chiropractor THANKS DOC)


my 79 has a/c but it didnt have a good compressor,  after the wreck i got a compressor that was said to "work great" and all the other parts are there but again do i need to get a new dryer can??


orifice tube?   where are they?? 

 how long should the vacuum pump run ??

can you calibrate the guages?? ( Doc's guages dont read right)

[*** YELLER ***]

as far as I know if you open the system then you need to replace the filter in the tube
i used a reman from napa in the blazer and it works great
I think if you get a reman comp and replace it right away and dont let anthing get into it it should be fine 

GOOOD LUCK BUDDY


 

[79coyotefrg [OP]]

very good answers to my questions

Reman is ok I guess, better than used I would think. Is the refrigerant R134a? If so the oils is polyester and will suck up moisture like a sponge if left open.
 You should change the drier if possible, but in a pinch you could dry it out in the oven at about 150 for a couple hours. Keep in mind this does nothing for cleaning out the trash.

 The orifice should be in the small line just before where it goes into the firewall. There will be a nut in the line and a funny shape where it goes in. Take the nut loose and pull it out with needle nose pliers. This can be cleaned out with brake clean and compressed air.

 DO NOT blowout the system with compressed air. That will just contaminate the system with moisture.

 

The longer you keep the vacuum pump on it the better. Moisture boils at a lower pressure and that will help insure a clean dry system.

 

Yes the gauges can be calibrated. Remove the face and turn the small screw either direction till the needle is on 0. Make sure the hose is open to the atmosphere.

[hilux-1983]

 

[79coyotefrg [OP]]

some more general A/C tech



Components of Automotive Air Conditioning

Your air conditioning system is made up of a compressor, a condenser, an evaporator (or drier), refrigeration lines and a couple of sensors here and there.

  Compressor: This is the heart of your a/c system. The compressor is what takes the refrigerant (the gas) and pressurizes it so it will cool the air. It's run by an engine belt. The compressor also has an electrically operated clutch that turns the compressor on and off as you demand more cool air.


Condenser: The condenser is like a miniature radiator, usually mounted at the front of the car right next to your big radiator. Sometimes the condenser will have its own electric cooling fan, too. The hot, compressed air passes through the condenser and gets lots cooler. As it cools, it becomes a liquid.

ORIFICE TUBE

The orifice tube, probably the most commonly used, can be found in most GM and Ford models. It is located in the inlet tube of the evaporator, or in the liquid line, somewhere between the outlet of the condenser and the inlet of the evaporator. This point can be found in a properly functioning system by locating the area between the outlet of the condenser and the inlet of the evaporator that suddenly makes the change from hot to cold. You should then see small dimples placed in the line that keep the orifice tube from moving. Most of the orifice tubes in use today measure approximately three inches in length and consist of a small brass tube, surrounded by plastic, and covered with a filter screen at each end. It is not uncommon for these tubes to become clogged with small debris. While inexpensive, usually between three to five dollars, the labor to replace one involves recovering the refrigerant, opening the system up, replacing the orifice tube, evacuating and then recharging. With this in mind, it might make sense to install a larger pre filter in front of the orifice tube to minimize the risk of of this problem reoccurring. Some Ford models have a permanently affixed orifice tube in the liquid line. These can be cut out and replaced with a combination filter/orifice assembly.


Evaporator: The evaporator is another little radiator that does just the opposite task as the condenser. As the super-cool liquid is passed through its tubes, air is forced through and gets really cold, right before it hits your face. As it warms up again, the refrigerant starts turning back into a gas.

Thermal Expansion Valve: You don't always want to freeze your toes off, so the a/c system has a valve that controls the flow of super-cool refrigerant to the evaporator. This way you can regulate how cold the air blowing on you gets. There are a few types of valves in use these days, but they all do the same thing.


Another common refrigerant regulator is the thermal expansion valve, or TXV. Commonly used on import and aftermarket systems. This type of valve can sense both temperature and pressure, and is very efficient at regulating refrigerant flow to the evaporator. Several variations of this valve are commonly found. Another example of a thermal expansion valve is Chrysler's "H block" type. This type of valve is usually located at the firewall, between the evaporator inlet and outlet tubes and the liquid and suction lines. These types of valves, although efficient, have some disadvantages over orifice tube systems. Like orifice tubes these valves can become clogged with debris, but also have small moving parts that may stick and malfunction due to corrosion.


Drier or Accumulator: The drier, also known as the receiver-drier, is sort of the safety catch for your system. The compressor is only supposed to compress the gas form of your refrigerant. However, there's always a chance that some liquid could make it back that far. The drier catches this liquid before it can damage your compressor. Since even the tiniest leak or careless installation can introduce water moisture to the system, the drier absorbs this chemically, using what's called a dessicant (similar to that packet of "DO NOT EAT" that comes with electronics). The drier also has a filter that catches any gunk that might be in there.

[79coyotefrg [OP]]

[79coyotefrg [OP]]

[twistedtoy92]

we are doin ac in class right now, pretty simple stuff really!  I love the old R12 systems, the freon is spendy but it will throw out around 39 degrees from the vent  if you have a TXV system (thermal expansion valve) system then you have a receiver/dryer and if you have a FOT system (fixed orifice tube) then you have an accumulator ..... i believe your yota has the FOT, and yes I would replace accumulator.

[79coyotefrg [OP]]

we are doin ac in class right now, pretty simple stuff really!  I love the old R12 systems, the freon is spendy but it will throw out around 39 degrees from the vent   if you have a TXV system (thermal expansion valve) system then you have an accumulator and if you have a FOT system (fixed orifice tube) then you have a receiver/dryer..... i believe your yota has the FOT, and yes I would replace the dryer.

thanks, 

does the suburban have the TXV

[cruiserfj45]

Toyota's have txv (thermal expansion valve).  Most American cars have fixed orifice tubes.  I just serviced an 88 toy pickup with r-12 and center vent temp was 32 degrees.  r134 I only see in the low 40's on even brand new Toyota's.

[79coyotefrg [OP]]

i'd LOVE to snag some R12 but its very

[kneedownnate]

I got very lucky and was able to fill the system on my 81 toyota twice with r12.  That was in the top 2 best a/c I've had!

[hilux-1983]

I'm still trying to figure out why my compressor will not come on. The compressor is fine, it's just not getting 12 volts to it to turn it on. I installed a new a/c anplifire(that's how toyota spells it) and I can hear it working but voltage still does not reach the compressor. I discharged the r-12 and took the evaporator case out and tested the low pressure switch and the expansion valve. They seem to be in spec. I found a relay that may not be working properly but I wont know till I put it all back together. I found out from the place that evacuated the r-12 that it is costing about $75.00 a lb.

[kneedownnate]

Why not put power to the relay and check to see if it comes out the right post?

[hilux-1983]

Why not put power to the relay and check to see if it comes out the right post?

I did and it wasn't getting any power. There was NO room to check the low pressure switch so that's why I went the route I did

[79coyotefrg [OP]]

there could be a vacuum switch problem,  personally i'm going to wire mine to a toggle,  i'm gonna try and do that today