A/C Problem

[Jim 99 PS]

I have a 1999 7.3 F-350. The A/C blows ice cold, for a while, then blows warm. The hotter it is outside, the shorter it blows cold.

I take it to the shop and they say, oh a 99 ford, we see that all the time, the compressors get internal shorts caused by excessive heat. Basically the short is thermally sensitive so you just replace your compressor. We can fix it now for only $1300.

I left.

I think it is a sensor in the A/C system. Has anyone else encountered this type of issue?

[gbear]

It sounds like it is going out on high head pressure. Someone needs to put gages on the system and see what is going on. It could be the high pressure switch of something else, also could be low on refrigerant and going out on low pressure. Only the gages will tell.

Jim

[smoken250]

Originally Posted by Jim 99 PS

I have a 1999 7.3 F-350. The A/C blows ice cold, for a while, then blows warm. The hotter it is outside, the shorter it blows cold.

I take it to the shop and they say, oh a 99 ford, we see that all the time, the compressors get internal shorts caused by excessive heat. Basically the short is thermally sensitive so you just replace your compressor. We can fix it now for only $1300.

I left.

I think it is a sensor in the A/C system. Has anyone else encountered this type of issue?

The compressor has an internal overload inside. When it gets hot the overload (switch) opens and cuts the compressor off. I would start by cleaning your condenser coil real good. If it was going out on low pressure it would be worse when it was just cool outside, it would freeze up. I would try to clean the coil before putting gauges on it due to the small amount of freon it the circuit. You would loose enough freon by putting gauges on to mess the charge up.

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Last edited by smoken250 : 03-21-2007 at 04:55 PM.

[gbear]

Cleanning the condenser is a good idea and dirty condenser makes high head pressure. But if that dosen't fix it i would put a set of gages on the system.

Jim

[Jon]

see many compressor issues with these trucks other then the clutches. The condensor is a big issue because it gets really dirty. I clean them all the time and notice big diff's in temp.

[willypscustoms]

i have the same prob and i know my ac is charged its not low but i still have this prob it will blow really cold then start to blow warm if im on the freeway it blows cold all the time but in town driving it will blow cold then after a while it will blow warm. i have not found the fix to this prob. people tell me to replace the compresser is this the only way to fix it?

[gbear]

I totally agree, "Clean the condensor" that is the only way the heat is removed from the system. air flow across the condensor is needed to remove it. Bugs, Lint and dirt cause big problems with them.

Jim

[Jon]

Removed the cover on the condensor box you would freak out!

[Jim 99 PS]

Thanks for the responses, so it seems possible that the faster I drive the more that is air pushed over the condensor as willypscustoms mentioned in his post. Running 80 always seems to keep it running cool.

So, where is the condensor box and is it hard to open and clean?

[07 Crash Wrench]

Hi,
Also Check your cluch fan..
clean the little spring on thefront of fan hub ( some do have , some don't ).
Try using a " LOW PRESSURE " air nozzle ( so you do'nt bend the fins ) to clean not only the condensor,
but also the radiator , intercooler,trans. ect.
blow the air in revervse direction of flow.
using water can bend the fins, then when everything dries it gets sucked backinto the coolers.

If your running around town mostly, or utility work - add a electric flexy fan in front of all the coolers.
tie in a relay to A/C and\or manual switch.

get the gauges on the system , if you have to "open up" for repair check the
orrfice tube to see if clogged up.

Later , Mark