No Heat.......Sometimes - Ranger-Forums - The Ultimate Ford Ranger Resource


General Technical & Electrical General technical and electrical discussion for the Ford Ranger that does not fit in any other sub-forum.

Reply
 
LinkBack Thread Tools Search this Thread
  #1  
Old 01-29-2015
Member
Thread Starter
 
Join Date: Nov 2014
Location: Meriden, CT
Posts: 3
No Heat.......Sometimes

Hey everyone, I have a 2000 3.0 ranger and I've been having some issues with the heat. Before, my truck would sometimes blow cold air and the temperature gauge would keep rising and overheat. Then, all of a sudden it would start blowing hot air and the temperature gauge went right back down. We thought it was a sticking thermostat so we changed that a few days ago. Now the past two days, my truck would only blow hot air if i had my foot on the gas. As soon as i hit a red light of had to stop it would turn to cold, then as soon as I start going again it went back to hot. We are so confused with this problem and don't want to blow money at a garage if someone out there has had this problem an =d knows what it is, thank you very much! -Heather
Reply With Quote
  #2  
Old 01-30-2015
RF Veteran
iTrader: (1)
 
Join Date: Jan 2014
Location: Vancouver, BC
Posts: 7,573
Original issue reads more like an air pocket in the cooling system, water pump can not pump air so you get an "air block" until enough pressure builds up to push it thru heater core, this cause the high temp and no heater heat, then lowering temp and heater heat returns.

It now reads like your heater core is partially blocked.

I would check that first.
Cold engine
Drain some coolant out into a bucket to reuse, just need enough out so alot won't come out the heater hoses.
Remove the heater hoses but at the bypass valve/heat controller valve not the firewall
Point one of the hoses down at the ground
Turn on garden hose, low flow, and hold it against the end of the other hose
Watch the flow out of heater core.
Switch heater hoses, i.e. reverse the flow
Watch the flow

You can increase garden hose flow as you see fit but always start low.

If it seems to be partially blocked, blow out water from core with your mouth on a hose, or compressor but low pressure.
Mix up some warm water and CLR, pour it into the core and wait 15-20min, then flush core again, in both directions
Repeat CLR as you see fit.


Why hot and cold?
If flow thru the core is limited the heat it provides is limited to the replacement of that heat from the engine heat.
At idle the flow is less, so blower fan uses it up pretty quick, at higher rpms the flow increases so replaces the heat in the core.

If core flow seems fine check bypass while it is disconnected.

Take pictures or mark hoses because you WILL forget which hose went where, lol.

When refilling a cooling system unhook one of the heater hoses, highest one, this will allow air to escape while filling up.

Last edited by RonD; 01-30-2015 at 12:49 PM.
Reply With Quote
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Heat blower stopped, then started, now stopped heat works nanookc General Technical & Electrical 4 02-17-2015 02:18 PM
Valves Chattering sometimes brow_tines 4.0L OHV & SOHC V6 Tech 18 05-01-2011 02:11 AM
most of the time it starts sometimes it dont wingnut 4.0L OHV & SOHC V6 Tech 6 09-07-2005 07:06 AM
ABS light comes on...sometimes jtfoxman General Ford Ranger Discussion 6 07-25-2005 11:31 AM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -6. The time now is 09:27 AM.


We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.